Fiber Optics Illustrated Dictionary - Part 38 doc

Fiber
Optics
Illustrated
Dictionary
Fibre Channel Loop Community
FCLC.
A
Cali-
fornia-based
organization
supporting
and
promoting
Fibre
Channel
technology
with
particular
attention
to
mass
storage
in
arbitrated
loop
topologies.
The
FCLC
merged
into
the

Fibre
Channel
Assocation
as
a
working
group
in
1999.
Fibre
Channel
Topologies
point-to-point
topology
Direct
connections
between
two
N
ports
wherein one
is
a server. This
is
a
nonscalable
topology
by
definition
and

arbitration
is
not
required.
arbitrated
loop
topology
A
topology
in
which
multiple
devices
can
share
the
media.
It
is
a
middle
solution
be-
tween
the
limited
point-to-point
topology
and
the

more
flexible
but
also
more
com-
plex
fabric
topology,
a
compromise
suit-
able for small local area networks
(LAN
s).
Because
resources
are
shared,
only
one
device
con
connect
at
anyone
time
to
a
shared

resource.
Devices
can
be
chained or arbitrated through a Fibre
Channel
hub.
fabric
topology
The
most
powerful
and
potentially
com-
plex
implementation
of
Fibre
Channel,
fabric
topology
encompasses
more
than
one
FC
switch
interconnected
to

other
de-
vices
through
one
or
more
ports.
F
ports
enable
connections
to
other
F
ports
or
to
N
ports
(node
ports).
Fibre Channel specifications
FCS.
There
are
two
general
aspects
of

FC
specifications,
the
ANSI
Fi-
bre
Channel
Standard
(X3Tll)
and
FCSI
Fibre
Chan-
nel
Profiles
developed
by
the
Fibre
Channel
Asso-
ciation
(now
the
Fibre
Channel
Industry
Association)
to
assist

implementors
in
understanding
and
devel-
oping
the
technology
while
maintaining
interoper-
ability.
See
Fibre
Channel
Standard,
Fibre
Channel
Industry
Association.
FibreChannelStandard
FCS.
A
high-speed,
block-
oriented,
serial,
fully
bidirectional
data

transfer
in-
terface
for
interconnecting workstations, main-
frames,
display
peripherals,
and
storage
devices.
Both
electrical
and
optical
media
are
supported
by
the
standard.
FCS
has
been
standardized
by
the
ANSI
X3TII
committee.

The
Fibre
Channel
Standard
is
intended
to
support
both
wire
and
fiber
optic
systems,
from
133
Mbps
to
1062
Mbps
(
and
higher)
at
distances
up
to
10
ki-
lometers

(contrast
this
with
a
standard
SCSI
electri-
cal
cable
transmission,
for
example,
which
has
a
practical
distance
of
only
a
few
feet).
The
actual
maximum
distance
is
dependent
upon
the

medium
and
data
rates.
For
example,
single-mode
fiber
can
transmit
up
to
10
kilometers, whereas shielded
362
twisted-pair
wire
has
a
limit
of
50
to
100
meters,
de-
pending
upon
whether
the

data
rate
is
25
or
12.5
MBps.
Frame
sizes
may
be
up
to
2,148
bytes,
depend-
ing
upon
the
size
of
the
payload
(the
informational
content).
Development
is
underway
to

support
higher
speeds
(e.g.,
10
Gbps).
There
are
three general topologies (architectures)
described
for
Fibre
Channel
networks.
FCS
provides
excellent
opportunities
for
aggregat-
ing
peripherals
under
desks,
or
in
server
rooms
and
secure

areas,
for
standardizing
a
wide
variety
of
com-
puter peripherals,
and
for
increasing architectural
flexibility
in
the
placement
of
equipment.
Because
it
is
a
hot-swappable
format,
Fibre
Channel
devices
can
be
added

to
or
removed
from
a
network
without
pow-
ering
down
the
network.
FCS
is
a
hierarchical,
layered
architecture,
with
five
layers
defined
from
highest
to
lowest.
Six
data
rate
speeds

have
been
defined
as
part
of
the
Fibre
Channel
Standard.
Cable
Rate
Payload
Rate
Max.
Distance
Mbaud
MBps
Mini-Coax 9
Ilm
Fiber
132.8125
12.5
35m
10km
265.6250
25
25m 10km
531.2500
50

15m
10km
1062.5000
100
10m
10km
2125.0000
200
4250.0000
400
See
F
port,
Firewire,
FL
port,
N
port,
storage
area
network.
See
Fibre
Channel
Layers
chart
and
other
entries
prefaced

by
Fibre
Channel.
Fibre Channel Systems Initiative
FCSI.
A
group
organized
in
1993
to
promote
the
interoperability,
use,
and
distribution
of
Fibre
Channel
technologies.
FCSI
Profiles
serve
as
guidelines
for
the
implementation
of

fiber
channel
systems
that
can
be
used
by
compo-
nent
manufacturers
and
systems
and
service
integra-
tors
of
fiber
communications
technologies.
See
Fi-
bre
Channel
Industry
Association.
Fibreoptic Industry Association Limited
FlA.
A

professional
organization
representing
suppliers,
edu-
cators,
and
installers
in
the
fiber
industry,
inaugurated
in
February
1990.
The
FIA
is
managed
from
the
U.K.
by
the
FIA
Secretariat
with
support
from

a
manage-
ment
council
of
elected
individuals
taken
from
FIA
members
and
other
supporting
individuals.
The
or-
ganization
includes
a
number
of
semi-autonomous
regional
offices.
/>Fick's first law
The
mass
movement
of

atoms
(flux)
from
one
point
to
another
in
a
given
time
frame
is
equal
to
the
negative
diffusivity
times
the
delta
con-
centration
(the
mass
per
given
volume)
divided
by

the
delta
diffusion
distance
as
expressed
for
a
one-
dimensional
system
by
F=-D(OC/&)
For
the
condition
C(A)
=
0,
the
equation
can
be
© 2003 by CRC Press LLC
simplified
to
F =
D(C(O)/A.)
As
applied

to
biological
systems,
the
net
rate
of
dif-
fusion
ofa
gas
across
a
fluid
membrance
is
propor-
tional
to
(a)
the
difference
in
partial
pressure,
(b)
to
the
area
of

the
membrane,
and
inversely
propertional
to
the
membrane's
thickness.
Fick's
second
law
describes
the
time-variant
diffu-
sion
of
atoms
in
a
material
for
a
one-dimensional
sys-
tem
(e.g.,
unidirectional
diffusion

from
aplanar
sur-
face)
for
a
constant
diffusion
coefficient.
This
facili-
tates
approximations
for
various
factors
related
to
diffusion.
See
diffusion.
FID
Field
Identifier,
part of
an
ISDN
Service
Profile
Identifier.

See
SPID.
FidoNet
Established
in
1984
by
Tom
Jennings
with
the
second
node
belonging
to
John
Madill,
this
net-
worked
bulletin
board
system
(BBS)
became
a
ma-
jor
communications
tool

for
techie
discussions,
email,
and
file
transfers
as
bulletin
board
operators
all
over
the
country
started
to
establish
Fido
boards
for
their
local
users.
field
In
a
scanning
video
broadcast

display,
a
field
is
every
other
line
of
the
full
picture
frame.
Thus,
it
is
all
the
odd
numbered
lines
taken
together,
or
all
the
even
numbered
lines
taken
together,

in
an
interlaced
image.
field,
data
A
record-holding
or
record-entering
en-
tity
in
a
database.
The
definition offield
types
facili-
tates
program
setup,
management,
and
data
manipu-
lation
by
alerting
the

software
as
to
the
nature
of
the
information
being
entered
into
a
field.
That
is,
a
field
may
be
given
a
data
type
(number,
string,
date,
etc.),
or
it
may

be
untyped,
but
either
way
this
tells
the
sys-
tem
something
about
the
data.
field mode
In
video
image
capture,
a
mode
that
cap-
tures
only
half of
the
scan
lines
in

order
to
save
an
image
in
lower
resolution,
thus
taking
less
storage
space.
See
field,
frame
mode.
field winding A
mechanism
for
energizing
electro-
magnets
in
a
generator.
See
winding.
Field, CyrusWest(1819-1892)An
American

indus-
trialist
who
contributed
significantly
to
the
economic
and
political
negotiations
involved
in
the
first
trans-
atlantic
telegraph
cable,
originally
completed
in
Au-
gust
1858
and
later successfully installed
as
a
per-

manent
cable.
The
concept
was
championed
in
part
by
Canadian
inventor Frederic
Gisborne,
who
ap-
pealed
to
the
American
business
community
for
fi-
nancing
so
he
could
establish
eastern
Canadian
tele-

graphic
installations
through
a
combination
of
steam-
ships
and
undetwater
cables.
Maritime
Canada
was
a
sparsely
populated
wilderness
at
the
time,
with
a
great
need
for
communications
links
and
limited

re-
sources
for
their
development.
As
a
youth,
Field
was
apprenticed
to
a
prominent
and
successful
merchant
before
setting
up
his
own
paper
manufacturing
firm.
He
thus
had
an
established

net-
work
of
contacts
in
the
New
York
and
Washington,
D.C.
areas
that
he
could
draw
upon
for
support.
As
a
successful businessman,
he
probably could
have
avoided hazardous and technologically difficult
projects,
but
the
telegraph

cable
idea
evidently
fired
his
imagination.
After
considering
the
feasibility
of
the
project,
with
help
from
his
brothers
and
other
busi-
ness
associates,
Field
contacted
influential
people
for
technical assistance and support (e.g., Samuel
Morse).

Cyrus
Field - Transatlantic
Cable
Installer
Cyrus
Field achievedfame for his contributions
to
the
laying
of
the
first transatlantic communications
cable.
His
portrait
was
widely used
in
articles and
song sheets commemorating
the
historic
event.
[Por-
trait
from
the
Mathew
B.
Brady

studio,
ca.
1850s.
Li-
brary
of
Congress
American
Memory
collection.}
Over
the
next
decade,
Field,
Taylor,
Roberts,
and
Cooper
made
substantial
investments
in
the
venture,
with
the
project's
promotional
lead,

Cyrus
Field,
re-
ceiving
most
of
the
public
acclaim
for
the
ambitious
project.
In
time,
the
Canadian-American
alliance
interlinked
maritime Canada
and,
after initial failure, linked
Canada
to
the
u.S.
through
the
Gulfof
St.

Lawrence.
These early trial-and-error cable installations
no
doubt
provided
valuable
technical
experience
facili-
tating
the
development
of
longer,
ocean-laid
cables.
In
1856,
Field
traveled
to
England
on
behalf
of
the
transatlantic
cable
project
and

formed
the
Atlantic
Telegraph
Company.
In December
1861,
George
Opdyke
wrote
to
President
Abraham
Lincoln
in
sup-
port
of
the
project.
No
doubt
other
supporters
made
similar
appeals
to
prominent
dignitaries.

The
Library
of
Congress
and
Cornell
archives
include
examples
of
correspondence
and
letters of
introduction
from
Cyrus
Field
to
prominent
persons,
including
the
Presi-
dent.
These
were
turbulent
times
in
America,

how-
ever,
and
the
pursuit ofa
cable
communication
with
the
British
Isles
wasn't
the
easiest
cause
to
champion
in
view
ofBritish-American
relations.
In
spite
of
the
technical
and
political
difficulties,
success

was
finally
363
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
achieved after several failures and temporary
successes,
with
a
permanent
cable
installed
in
the
mid-1860s.
Instantaneous
intercontinental
communi-
cation
was
now
possible,
a
revolution
that
forever
changed

humankind's
commercial
and
social
inter-
actions.
After
the
laying
of
the
transatlantic
cable,
Field
be-
came
an
advocate
for
the
public
acquisition
of
com-
munications
services.
To
gamer
support
for

this
con-
cept,
Field
penned
an
article
called
"Government
Te-
legraphy"
for
the
North
American
Review
in
March
1886
that
states,
in
part:
"It
appears
to
me
that
the
time

has
arrived
when
the
Government
of
the
United
States
should
pur-
chase,
in
the
interest
of
the
people,
all
the
telegraph
lines
in
the
country

Communication
by
telegraph
has

become
almost
as
common,
and
quite
as
nec-
essary,
as
communication
by
letter

As
letters
are
sent
to
all
parts
of
the
United
States
for
two
cents,
and
papers

and
magazines
at
one
cent
for
every
four
ounces,
so,
I
think,
a
telegraph
message
should
be
sent
to
any
part
of
the
United
States
at
the
low-
est
price

at
which
experience
has
shown
it
possible
that
the
transmission
can
be
effected

"
An
illustrated
history
of
the
Atlantic
Telegraph
Com-
pany
is
available
on
the
World
Wide

Web.
See
Gisbome,
Frederic
Newton;
gutta-percha;
transatlan-
tic
cable.
/>FIF
See
Fractal
Image
Format.
FIFO
first
in,
first
out.
In
programming,
a
means
of
processing
data
so
the
fIrst
item

to
be
stored
or
placed
on
a
stack
is
the
first
to
be
fetched,
moved,
or
dis-
carded.
Imagine
a
narrow
vertical
tube
for
gerbils
(or
hamsters,
if
you
prefer

fluffy
rodents);
the
first
ger-
bil
to
squeeze
in
through
the
top
is
the
first
to
slide
out
the
bottom.
In
general
terms
of
telecommunica-
tions,
in
a
FIFO
system

the
first
person
who
calls
is
the
first
to
be
referred
to
an
agent.
Fiber
Optic
Filament
Spools
Spools
oj
fiber opticfilament
are
soldfor a variety
of
lighting and hobby applications, including
signs,
lamps,
and artpieces
in
sizes rangingfrom about .25

to
2.0
mm.
Sheathedfilaments that
can
be
separated
from
the
main
cable
as
needed
are
also
available.
fllament
1.
A
fine
metal
conducting
wire
commonly
used
in
tubes
and
bulbs.
By

passing
a
current
through
a
filament
in
a
specialized,
enclosed
environment,
it
364
becomes
incandescent,
giving off
tight.
See
cathode.
2.
A
fine
cylinder
of
glass
or plastic.
In
fiber
optics
technologies,

glass
or
plastic
filaments
with
good
conducting
properties
(e.g.,
clear
glass
with
a
mini-
mum
of fabrication
blemishes
and
impurities)
are
used
as
waveguides
for
the
conduction
of
light
sig-
nals.

They
are
popular
as
novelty
fiber
optic
lamps,
signs,
art
pieces,
and
for
communications
technolo-
gies.
See
fiber
optics.
file
A
collection
of
associated
data
stored
so
that
a
pointer

to
the
information
identifies
and
encompasses
the
contents
of
that
file
as
an
accessible,
readable
unit,
even
if
stored
in
separate
parts.
This
is
one
of
the
most
common
units

of
storage
in
a
computer
system
-
file
hierarc~ies,
file
folders,
file
types,
and
file
manage-
ment
are
all
computer
structures
and
processes
con-
structed
to
manage
files.
file
attachment

Most
email
systems
are
text-oriented
7-bit
messaging
media.
So
how
do
you
send
some-
one
an
8-bit
binary
file?
To
meet
this
need,
many
text
email
systems
have
the
capability

of
sending
binary
files
as
file
attachments
to
a
message.
Since
binary
files
include
symbols
and
characters
which
cannot
be
displayed
in
aplain
text
window,
and
since
the
sym-
bols

are
not
meaningful
to
humans,
it
is
more
practi-
cal
to
send
the
file
(which
may
be
sound,
graphics,
or
a
computer
application)
as
an
attachment,
rather
than
as
a

postscript
to
the
email
text
message.
In
most
cases,
all
that
is
necessary
is
to
specify
the
name
of
the
file
in
the
Attachment:
text
box
or
email
message
header,

and
the
system
will
take
care
of
the
transfer
of
the
information.
file
cache
An
area
of
memory
allocated
by
an
oper-
ating
system
or
computer
applications
program
to
temporarily

store
a
file
that
may
need
to
be
accessed
or
modified
frequently.
Many
database
and
spread-
sheet
programs
use
file
caches
to
allow
quick
updates
and
redisplays
of
information,
and

the
data
may
also
be
periodically
stored
on
disk
as
a
background
task
so
as
not
to
lose
information
and
updates
in
the
case
of
a software crash
or
power outage.
file
extension A syntactic

convention
that
aids
in
identifying
computer
data
file
types.
There
8Je
many
categories
of
computer
files:
text
files,
graphics
files,
sound
files,
and
within
these
basic
categories
are
many
subcategories,

such
as
JPEG,
TIFF,
etc.
A
con-
vention
of
adding
a
period
and
a
short
SUffIX
to
iden-
tify
the
type
of
file,
so
it
can
be
found
at
a

glance,
has
become
widespread,
and
some
applications
and
systems
will
even
enforce
certain
file
extensions.
Since the mid-1980s, every significant microcom-
puter
and
workstation
level
operating
system
except
MS-DOS
has
allowed
file
extensions
of
reasonable

length
(up
to
16,
32,
64,
or
256
characters
for
the
whole file name, depending upon the system).
MS-DOS
restricted
its
users
to
only
three
characters
and
enforced
the
use
of
the
period
(dot)
as
the

file
extension
symbol.
Since
there
were
so
many
DOS-
based
machines,
users
of
other
systems
hact
to
trun-
cate
file
extensions
(and
the
rest
of
the
file
name)
when
transferring

files
to
other
systems.
This
imprac-
tical
three-character
extension
limit
is
still
prevalent,
© 2003 by CRC Press LLC
even though most Windows-based systems now
support longer
filenames
(it
is
still
common
to
see
HTML
file
extensions
on
the
Web
listed

as
".hOO"
instead
of
".hool").
On
most
other
systems,
the
dot
(.)
is
not
mandatory
for
specifying
the
extension.
The
user
can
save
a
file
with
no
dots
or
with a

dozen
dots.
However,
since
several early systems
in
the
1970s
required a
dot,
users
are
used
to
this
naming convention.
On
many
systems,
a
file
extension
also
lists a
ver-
sion
number,
so
backups
and

revision histories
can
be
maintained
at
all
times.
For
example,
the
follow-
ing
extensions
may
be
automatically generated:
~atimage.tiff.locmygreatimage.tiff;l
mygreatimage.
tiff.
2
or
mygreatimage.
tiff;
2
mygreatimage.
tiff.
3
oc
mygreatimage.
tiff;

3
If
the
default
for
the
revision level
is
three, then
the
next
file
to
be
saved under
the
same
name
will
su-
persede
the
oldest
file,
in
a first
in,
first out
(FIFO)
sequence,

so
that
no
more
than
three
files
with
the
same
name
are
stored
at
anyone
time.
This
version
number extension/revision system
is
very handy
when
something
is
saved accidentally,
and
the
pre-
vious
version

needs
to
be
retrieved.
fIle
gap A
blank
inserted
to
indicate astopping
point,
or adivision between
sets
of
infonnation, especially
on
a sequential
file
recording
system.
On
an
audio
tape
or
digital data
tape,
a
file
gap

indicates
the
be-
ginning
or
end
ofa
song
or
file.
file
server
Generally,
asystem
on
anetwork that
ad-
ministrates
the
storage
of
and
access
to
files,
often
through a client/server model,
in
which
multiple

us-
ers
make
requests
to
the
file
server through
the
cli-
ent
software.
This
system reduces redundant storage
of
files
on
individual
systems
and
makes
it
easier
and
faster
to
update individual files. The server also
handles
file
locks,

so
data
files
cannot
be
simulta-
neously updated
and
saved
by
multiple users.
Usu-
ally,
a
dedicated
file
server
is
equipped
with
high
stor-
age
capacity,
and
it
may
manage security levels
for
access

to
the
files.
Network File
System
(NFS)
is
a
commonly
used Unix
file
server system
from
Sun
Microsystems that
is
implemented
on
many plat-
fonns.
file
server, Frame Relay
In
aFrame Relay network,
the
file
server
is
a device that provides connections
with terminals, controls transmission

flow,
and
pro-
vides
end-to-end
acknowledgment
and
error
recovery.
File Service Protocol
FSP.
A
file
transfer protocol
somewhat similar
to
File Transfer Protocol
(FTP)
originally developed
for
Unix
by
Wen-King
SUo
It
is
a low-load (nonforking), reasonably robust protocol
that permits transfers
to
be

resumed
from
the
point
at
which
they
stopped
if
the
server
goes
down
tem-
porarily
or,
ifdesired, allows
for
partial
file
transfers
from
a specified point.
FSP
is
somewhat
like
Anonymous
FTP
except that

it
doesn't require a username and password. For
iden-
tification
and
logging purposes,
the
host
domain
of
the
user
is
recorded.
It
is
also
claimed that it
is
less
prone
to
server
attacks
than
systems
with
FTP
setVers.
FSP

relies
on
datagrams
rather
than
TCP
sockets
for
its
transmission connections
and
uses
the
same
port
for
communications.
See
File Transfer Protocol.
fIle
sharing
Access
by
more
than
one
user,
sometimes
at
the

same
time,
depending
on
the
nature of
the
data,
to
files
that
may
be
on
one
system
on
a network
or
spread out over several workstations that
are
inter-
accessible.
On
the
Apple Macintosh,
file
sharing
is
easily set

up
via utilities
in
the
Control
Panels
so
that
passwords
can
be
assigned
and
files
shared
with
des-
ignated users
on
the
system.
On
a larger
network,
a
particular machine
or
set
of
machines, usually with

large
hard disk storage capacity,
may
be
dedicated
to
file
serving
and
sharing activities.
See
file
server.
File Transfer Protocol
FTP.
A user-level
file
shar-
ing
protocol established by
the
early
1970s
on
the
ARPANET
and
now
widely implemented
on

the
In-
ternet
in
the
form
of
FTP
archive sites.
The
concept
of
FTP sites was
to
provide a simple, consistent
means
of
presenting
and
accessing
file
information
on
a variety oftypes
of
file
archive sites,
so
the
user

could easily navigate
the
site
and
upload
or
down-
load
files
unassisted.
In
other words,
FTP
sites
have
aconsistent
look
and
feel;
once you've learned a
few
easy
commands,
you
can
log
in,
look
around,
and

get
what you need without having
to
worry
about
the
in-
dividual characteristics
of
the system
on
which
the
files
are
stored.
Many
FTP
sites provide public access
through
auser
login
in
which
you
type
"anonymous"
as
the
user-

name,
and
your
full
email
address
as
the
password.
If
you
have
a
Unix
shell
account with
an
FTP
client,
you
simply
type
"ftp"(inalliowercase),
followed
by
"help" when
it
activates,
to
learn

its
basic
commands
and
capabilities.
The
inset shows
an
example
of
a
simple anonymous
FTP
login.
In
the
example session shown,
the
user
logs
in
as
anonymous,
supplies a legitimate email address
as
the password, and
is
dropped into a limited en-
vironment where basic directory traversing com-
mands

and
file
download
commands
can
be
used
The
message "Guest
login
ok,
access restrictions apply."
is
displayed.
This
session
is
very typical
in
that
the
user
is
prompted
to
disconnect
if
logging
of
his

or
her
activities
is
objectionable
and
is
notified
that
there
are
restrictions.
The
user's logon number
is
shown,
in
addition
to
the
total number
of
people
on
the
sys-
tem.
If
the
system

is
at
capacity,
the
user
may
be
asked
to
try
again
or
may
be
provided
with
amessage giving
the
addresses
of
mirror sites (sites with
the
same
files
in
other locations).
For
file
transfers,
the

get
command,
followed by a
filename, will initiate a file download.
The
com-
mands
bye or quit will end a session.
On
Unix systems,
you
can
type "man ftp"
at
a shell
prompt
to
read
the
manual pages
for
FTP,
which
in-
clude a list
of
common
commands.
FTP
file

down-
load capability
is
built into most
Web
browsers
and
works
transparently
with
many
Web
file archives.
Several variations
of
the
File Transfer Protocol ex-
ist,
and
cutdown, easier-to-implement versions have
also been developed, which are described
on
the
365
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
Internet

in
various
RFCs.
See
File
Service Protocol,
Simple
File
Transfer Protocol,
Trivial
File
Transfer
Protocol,
RFC
171,
RFC
172,
RFC
959.
file
transfer protocol
In
its
general
sense,
any
pro-
gram
that
facilitates

the
movement
of
files
from
one
system
to
another,
particularly
through
phone,
null
modem
or
other
serial
data
links,
or
the
Internet.
There
are
many
file
transfer protocols,
but
two
of

the
most
popular
implementations
are
ZModem,
for
telephone
line
transfers,
and
File
Transfer Protocol
(FTP)
for
Internet
transfers.
Other popular programs
include
Kermit,
XModem,
and
YModem.
More
detailed
in-
formation
is
included
in

this
dictionary
under
indi-
vidual
listings
for
the
various
protocols.
fIlm
n.
1.
A
thin
membrane,
skin,
or
coating.
2.
A
thin,
light-
and/or
chemical-sensitive
material
commonly
used
in
the

photographic
industry.
3.
The
collective
name
for
a
sequential,
related
set
of
still
frames,
taken
together,
form
a
story
or
cohesive
idea
that
is
viewed
by
playing
the
frames
through

a
projector.
Also
called
movie.
filter
n.
1.
A
porous
material
through
which
mixtures
are
screened
in
order
to
selectively
prevent
larger
bits
of
the
mixture
from
passing
through.
2.

A
device
or
material
through
which
particular
waves,
frequencies,
or
particles
do
not
pass.
Afilter
may
be
used
in
com-
bination
with
another
device,
such
as
an
amplifier,
in
order

to
filter
out
noise,
while
propagating
the
de-
sired
portion
ofa
signal.
Electrical
and
audio
filters
are
common.
fIlter,
fIle
File
filters
are
not
necessarily exclusion-
ary
tools,
as
in
some

senses
of
the
word
"filter,"
but
rather
may
be
conversion
utilities available
in
many
application
programs
to
input
or
output
files
in
a
for-
mat
that
is
not
native
to
the

application.
Thus,
a
TIFF
file
might
be
imported
into
a paint program
with
a
proprietary
format,
through
a
filter,
and
may
be
ex-
ported
through
another
filter
to
a
JPEG
file,
for

ex-
ample,
for
use
on
the
Web.
A
filter
may
also
be
coordinated
with
a
database
to
selectively
provide
access
to
higher
priority
messages
or
processes,
while
filtering
out,
or

queuing
those
of
lower
priorities.
Email
filters
are
especially useful
to
those
who
.get
hundreds
of
messages
a
day,
as
often
happens
on
email
mailing
lists.
A
good
email
client
will

let
you
set
up
filters
that
file
the
messages
in
sepa-
rate
folders
to
be
selectively
read
later,
so
the
user
can
more
easily
determine
which
messages
to
check
first.

Exclusionary
file
filters
also
exist.
For
example,
an
email
file
filter
may
exclude
all
messages
received
from

or
relegate
them
unread
to
the
bit
bucket.
fIlter,
network In
network
transmissions,

there
are
physical
filters
and
logical
filters.
Logical
filters
func-
tion
on
every
level
of
the
system
from
low-end
oper-
ating
functions,
to
high-end user applications.
Logi-
cal
filters
employ
algorithms
to

selectively block
the
continuation
of
certain
information,
such
as
extrane-
ous
packets,
unrecognized
characters,
extra
informa-
tion
not
supported
by
the
receiving protocol,
un-
wanted
email,
messages
from
sites
operating
unlaw-
fully,

etc.
366
filtering
Using
physical
or
logical
means
to
selec-
tively permit
access
ofonly
the
desired information.
Thus,
unwanted information
can
be
screened
out,
or
a
lower
capacity
system
can
be
used
to

view
or
use
part of
the
information according
to
its
capabilities.
F
or
example,
filtering out parts ofa transmitted
im-
age
makes
it
possible
to
display
it
on
a
system
with
low
resolution,
or
a
slow

image
display,
a solution
that
may
be
preferable
to
no
image
at
all.
See
com-
pression,
MPEG.
filtering agent, filtering client A
software
program
that
can
be
configured
to
selectively reject
or
keep
information according
to
a

set
of
parameters
or
keys.
With
the
excess
ofinformation available
through
the
Internet,
filtering
agents
are
increasing
in
importance.
See
data
mining.
filtering traffic
On
a
network,
the
selective
accep-
tance
or

rejection ofcertain packets,
messages,
or
processes according
to
a
set
ofpriorities
and
param-
eters.
High
and
low
usage
times
may
also
be
factors
in
setting
up
filtering instructions.
Traffic
filtering
is
usually accomplished
by
combining

a
database
with
a list ofpriorities.
See
firewall.
fm
waveguide A structure
that
can
be
used
in
con-
junction with circular waveguides
to
increase
the
range
ofwavelengths that
can
be
transmitted,
by
at-
taching a longitudinal
metal
fin.
Financial Services
Technology

Consortium
FSTC.
A
not-
for-profit consortium of
banks,
financial
ser-
vices institutions, technology companies, govern-
ment
agencies, research
labs,
and
educational
insti-
tutions.
FSTC
supports
and
promotes
collaborative
research
and
technical projects affecting
the
finan-
cial
services
industry
in

order
to
further
the
competi-
tive health
of
the financial industry in the U.S.
/>fmderA
name
used
on
several
computer
systems
for
applications
that
aid
in
locating
information
on
a sys-
tem,
whether it
be
files, directories, or
the
specific

content of
files.
Finder
On
the
Apple
Macintosh,
the
graphical
user
interface
and
operating system processes through
which
the
user interacts with
the
system.
Multifinder
allows
more
than
one
program
to
be
executed
at
a
time

and
is
available
on
the
more
recent
versions
of
MacOS.
It
is
also
a generic
name
for
a
file
fmding
tool
that
comes
with
the
operating
system.
finesse
In
optical resonating cavities,
the

number
of
round
trips
a light
pulse
can
make
from
one
reflec-
tive
surface
to
another
and
back
before
the
signal
dis-
appears
through
scattering
and
attenuation.
Finger
The
name
of

an
online information utility,
based
on
the
Finger Protocol,
that
allows
the
user
to
retrieve
and
display
information
about
users
ofa
sys-
tem,
or
the
owner
ofa
particular
account
on
the
net-
work,

provided
no
firewalls
exist
to
block
the
finger
command
(as
a
command
it
is
spelled
all
in
lower-
case).
Login
and
logout
times
may
be
displayed,
or
the
length
of

time
since
the
last
login.
If
the
user
que-
ried
has
particular
dot
files
configured,
such
as
.plan
(dotplan),
additional information
from
this
file
will
be
displayed. Users often
use
the
.plan
file

to
list
© 2003 by CRC Press LLC
philosophies,
home
addresses,
office
hours,
interests,
or
professional
credentials.
See
firewall.
Finger Protocol A network information protocol
which
is
an
elective
proposed
Draft
Standard
of
the
IETF.
See
finger,
RFC
1288.
Finkel, Raphael

A.
Finkel
is
probably
best
known
as
the
first
disseminator
of
the
infamous
Jargon
File,
distributed
from
Stanford
University
in
1975.
He
is
also
the
author
or
co-author
of
handbooks

and
numer-
ous
articles
on
networks,
data
structures,
and
com-
puter
algorithms.
See
Jargon
File,
The.
FIPS
See
Federal
Information
Processing
Standard.
frrefighting
Trying
to
fix
something
after
the
fact.

Often
used
in
a
derogatory
sense
to
indicate
the
frus-
tration
of
trying
to
rescue
a situation
that
would
not
have
occurred
if
proper
steps
or
prevention
methods
had
been
used

in
the
first
place.
The
term
describes
distressing,
expensive
catch-up
or
fix
-up
situations
resulting
from
bad
management
decisions.
For
ex-
ample,
shipping
a
software
product
before
it
is
fully

tested
and
debugged
can
result
in
a
great
loss
of
con-
fidence
on
the
part
of
customers,
and
enormous
ex-
tra
fire
fighting
expense
to
the
company
in
terms
of

subsequent
upgrades
and
tech
support
that
would
not
have
been
required
if
the
product
had
been
properly
completed
before
shipment.
firewall A physical screen created
to
prevent
the
spread
of
fire.
It
may
be

a
wall
of
heavy,
fire-resis-
tance
materials.
See
wiring
vault.
firewall, networkA
computer
network
security
con-
figuration
designed
to
limit
completely
or
selectively
access
to
a
system.
At
one
time,
firewalls

were
usu-
ally
implemented
on
a
specific
gateway
machine,
but
hardware
and
software
firewalls
now
are
set
up
in
a
number
of
ways,
using
filters,
proxies,
and
gateways
at
the

circuit
level.
A
network
traffic
firewall
exam-
ines
incoming
packets
and
selectively
lets
them
pass
through,
and
it
may
also
edit
outgoing
traffic
in
or-
der
to
protect
the
identities

of
the
senders,
as
in
some
government networks. Many local area network
(LAN)
frrewalls
are
one-way,
with
unlimited
access
out
of
the
LAN
and
selective
access
into
the
LAN.
Systems
with
firewalls
frequently
log
all

activities
through
the
point
or
points
of
entry,
with
or
without
notification.
See
packet
filtering,
proxy
server.
FireWire
FireWire technology, also known
as
LLINK,
is
a
real
breakthrough
for
connecting
a
wide
variety

of
peripheral
devices
to
computer
networks.
It
was
developed
in
the
mid-1990s
by
Apple
Com-
puter
and
quickly
moved
toward
broader industry
standardization.
In
2001,
the
National
Academy
of
Television
Arts

and
Sciences
(NATAS)
recognized
Apple's
FireWire
contribution
to
the
multimedia
in-
dustry
by
awarding
the
company
the
Primetime
Emmy
Engineering
Award.
The
Fire
Wire
serial
communications
data
rate
is
fast,

up
to
200
Mbps
when
it
was
first
released,
with
400
Mbps
supported
soon
after.
FireWire
cables
are
easy
to
connect
and
hot-swappable
(they
can
be
plugged
and
unplugged
without

rebooting
the
host
computer).
A
FireWire
bus
can
support
up
to
63
devices,
com-
pared
to
the
seven
devices
commonly
supported
by
most
computer
SCSI
buses.
The
format
is
autocon-

figuring,
so
it
isn't
necessary
to
set
or
keep
track
of
peripheral
ID
numbers
for
the
devices.
Fire
Wire
de-
vices
don't
need
to
be
terminated
by
the
user.
FireWire

is
a
good
standard
for
a
world
demanding
high-bandwidth
multimedia
applications.
It's
much
faster
than
USB
and
supports
isochronous
data
trans-
fers,
providing guaranteed bandwidth
for
realtime
audio/video
data
streams.
Many
vendors

have
devel-
oped
PCI-format
FireWire
cards
and
software
driv-
ers
for
computers
that
don't
have
native
support
for
Fire
Wire.
Cards
will
typically
support
between
one
::~S~;~~~~~~~~~l~~~:~I~fs
'.
likely
that

most
operating
systems
will
soon
provide
native
support
for
the
FireWire
(IEEE-1394x)
stan-
dard.
Peripheral
hardware
vendors
supporting
Fire-
Wire
include
Canon,
WC,
Kodak,
and
Sony.
By
Au-
gust
2001,

60
GByte
Fire
Wire
hard
drives
were
avail-
able
for
less
than
$200.
In
spring
2001,
the
1394
Trade
Association
intro-
duced
an
update
to
the
Fire
Wire
standard, called
1394b.

The
previous
speed
of
400
Mbps
was
already
ripping
fast
compared
to
previously
common
periph-
eral
bus
standards,
but
the
new
standard
increased
this
data
rate
even
further,
up
to

3.2
Gbps
over
glass
op-
tical
fiber
media.
The
updated
format
also
uses
a
new
bus
arbitration
scheme,
called
Bus
Owner
Supervi-
sor
Selector
(BOSS).
It
enables
pipelined
unidirec-
tional

arbitration,
in
parallel
with
data
transmission.
By
using
bilingual
mode,
the
1394b
specification
is
backwardly
compatible
with
previous
versions.
The
new
features
of
1394
are
available
in
beta
mode.
FIRMR

Federal Information Resources
Manage-
ment
Regulation.
firmware
Programmed
circuitry
that
is
semiperma-
nent.
Software
on
a
disk
is
easily
changed
and
rewrit-
ten.
Software
on
the
circuitry of a
microchip
is
not
easily
changed

and
rewritten.
In
between
these
are
EPROMs,
erasable,
reprogrammable
chips
which
can
be
changed
with
the
right
equipment,
and
which
re-
tain
the
information
during
a
power-off.
FIRST See Forum
of
Incident Response and

Se-
curity
Teams.
first call dateA
record
of
the
frrst
time
a
subscriber
line
is
used,
sometimes
used
in billing
or
in
settling
disputes.
first in, first out
See
FIFO.
fish job slang
Phrase
to
describe
a
difficult

wiring
installation
in
which
the
wiring
has
to
be
pulled
and
threaded
through
constricted
or
hard-to-reach
spaces.
fish tape slang A
smooth-surfaced,
nonconductive
(e.g.,
steel)
metal
tape
that
is
threaded
through
tight
areas,

such
as
a
wall
or
cable
conduit.
It
is
then
at-
tached
to
a
cable
so
that
it
can
be
pulled
more
easily
back
through
the
wiring
path.
See
pulling

eye.
fishbone antenna An
antenna
named
for
its
resem-
blance
to
the
ribs
ofa
fish
because
it
includes
a
se-
ries
of
coplanar
antenna
elements
arranged
in
pairs.
The
fishbone
antenna
is

used
in
conjunction
with
a
balanced
transmission
line.
367
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
Fisher,
Yuval
Author
of
Fractal
Image
Compression,
which
describes
the
current
knowledge
of fractal
compression
in
down-to-Earth

terms
with
C
source
code
examples.
See
fractal
transform.
FITL
See
Fiber
in
the
Loop.
FIX
Federal
Internet
Exchange.
fIXed
access
unit
FAU.
A
wireless
telephony
desig-
nation
for
a

wireless
phone
unit
that
is
not
intended
to
be
carried
around,
but
rather
to
provide
wireless
communications
within
a
limited
region.
Thus,
local
wireless
phone
service
can
be
installed
without

go-
ing
through
a
local
phone
provider,
much
like
a
fancy
intercom
unit,
or
it
can
be
subscribed
through
an
al-
ternate
vendor
as
a
limited
cellular
or
PCS
seIVice.

Fixed
End
System
F-ES.
Anonmobile
data
commu-
nications
system
through
which
a
mobile
subscriber
accesses
landline
network
services.
F-
ESs
typically
comprise
modems
installed
into
desktop
computers.
See
Cellular
Digital

Packet
Data,
Mobile
End
System.
Fixed
Radio
Access
FRA.
Local
telephone
service
based
upon
wireless
radio
technology
transmitted
to
an
antenna
attached
to
the
subscriber's
premises.
The
concept
did
not

catch
on
until
it
was
marketed
to
con-
sumers
as
plain
old
telephone
service
(POTS)
with
enhancements,
as
opposed
to
new
wireless
technol-
ogy.
The
concept
originally
was
more
prevalent

in
the
U.K.
than
the
U.S.,
but
it
is
beginning
to
influence
vendors
in
the
North
American
market.
In
typical
in-
stallations,
the
digital
signal
from
the
transceiver
is
converted

to
analog
and
carried
to
various
points
on
the
premises
through
the
existing
copper
wire,
but
the
digital
signals
can
also
be
fed
directly
through
newly
installed
fiber
optic
cables,

an
option
that
would
be
of interest
to
individuals
and
businesses desiring
wideband
high-speed
services.
The
local
loop
con-
cept,
in
which
a
network
of
about
20
base
stations
could
serve
a

community
of
40,000
population,
is
less
expensive
to
implement
and
serve
than
current
cel-
lular
systems
and
thus
could
serve
a
niche
somewhere
between
traditional
telephone
and
mobile
telephone
subscribers.

fIXed
satellite
service
FSS.
One
of
two
divisions
into
which
Ku-band
satellite
broadcast
services
have
been
split.
FSS
operates
in
the
11.7
to
12.2
GHz
range.
The
other
is
broadcasting

satellite
service
(BSS).
See
Ku-
band.
Fixed Telecommunications Network Service
FTNS.
A
category
of
licensed
service
recognized
by
communications
authorities
in
Hong
Kong.
There
are
various
types
of
services
that
constitute
FTNS,
in-

cluding
wireline,
cable,
wireless,
and
satellite.
FTNS
Operators
are
assigned
tariffs
on
the
basis
of
the
spe-
cific
types
of
services
they
provide,
such
as
voice
or
data.
Changes
in

the
provision
of
local
FTNS
were
made
in
1995
when the Hong Kong Telephone
Company's
franchise
expired,
and
the
service
was
licensed
instead
to
four
companies.
Fixed
Wireless
Access
FWA.
In
regions
where
the

cost
of
installing
wire
line
may
be
prohibitive,
due
to
rough
terrain
or
sparse
population,
or
where
regional
growth
outstrips
wireline
installation
capacity,
FWA
provides a long-term
or
temporary alternative.
It
368
combines

radio-based
phone
service,
in
the
place
of
the
local
wireline
loop,
with
common
carrier
phone
service.
See
time
division
multiple
access,
code
di-
vision
multiple
access.
Fizeau interferometer
See
interferometer,
Fizeau.

FK
foreign
key.
A
designation
in
a
key
cryptography
scheme.
See
key,
encryption.
FL
port
On
a
Fibre
Channel
network,
a
switch
that
connects
to
a
loop.
Middle
priority
addresses

are
as-
signed
to
FL
ports,
giving
them
higher
priority
than
N
ports
(node
ports)
and
lower
priority
(in
terms
of
loop
control)
than
an
end
loop
(NL
port)
endstation

port.
See
F
port.
flag
n.
1.
A
device
or
signal
used
to
attract
attention
or
to
indicate
the
state
ofa
situation.
In
software
pro-
gramming
and
network operation,
flags
are fre-

quently
used
to
indicate
the
state
of
processes
or
vari-
ables,
often
under
changing
conditions.
FLAG
Ltd. Fiberoptic
Link
Around
the
Globe.
A
commercial
fiber
services
carrier
with
installations
of
more

than
18,000
miles
of
fiber
optic
cable
in-
stalled
worldwide.
flame
resistant,
flame
retardant A
medium
that
is
inherently resistant
to
catching
fire
or
spreading
flames
or
is
treated
or
manufactured
to

increase
these
retardant properties.
Flame
resistant
and
retardant
materials
are
used
in
many
industries
including
con-
struction,
electrical
installation,
and
clothing
manu-
facture.
flammable A
property
of
easily
catching
fire
or
con-

tinuing
to
bum
readily.
flange
A
rim
or
rib
on
an
object
to
add
strength
or
to
aid
in
alignment.
flash
v.
On
a
phone
or
intercom
system,
to
send

a
sig-
nal
through
the
line
by
pressing
the
switch
button
on
the
handset
holder
or
the
button
designated
as
ajlash
button.
The
flash
button
is
used
on
some
local

multi-
line
systems
to
transfer a
call
and
may
be
followed
by
the
keying
in
of
the
number
of
the
extension.
flash
button A
button
designated
on
a
phone
or
in-
tercom

system
to
send
a
signal
that
is
the
same
as
pressing
the
switch
button
on
the
handset
holder.
See
flash,
flash
hook.
flash
cut
See
hot
cut.
flash
hook
See

switch
hook.
flash
interference
In
television
transmission
and
dis-
play,
a
flash
is
a
very
brief
interference,
sufficient
to
distort
the
picture
information.
flash
memory
A
type
of
nonvolatile,
rewritable

com-
puter
memory
technology,
developed
by
Intel,
pro-
viding
an
alternative
to
large
storage
devices.
Since
flash
memory
is
physically
compact
and
doesn't
lose
its
data
when
the
device
is

not
in
use,
it
has
been
in-
corporated
into
PCMCIA
cards
for
portable
comput-
ing
applications.
Flash
memory
is
also
starting
to
be
used
in
portable
telephone
devices
and
digital

cam-
eras.
See
memory,
PCMCIA.
flash tube A
bulb
or
tube
used
to
create
a
bright,
momentary
burst
of
illumination
through
application
ofa
high-voltage
pulse.
One-time
flash
bulbs
were
used
in
older cameras; electronically activated,

reusable
bulbs
are
now
common.
© 2003 by CRC Press LLC
flat connector
Any
of a
large
variety
of
electronic
connectors
that
are
basically
flat,
that
is,
wide
and
narrow.
Within
each
subset
of
connector
types
(power

cable
connectors,
data
cable
connectors,
etc.)
there
are
usually
some
that
are
called
flat
connectors
due
to
their
low
profile.
Flat
connectors
typically
contain
a
single
line
of
pins,
pads,

or
holes
for
coupling
with
cables,
backplanes,
or
components.
F
or
portable
devices,
a
flat
connector
is
a
small,
low-
resistance,
narrow
electronic
connector.
This
type
of
connector
is
increasingly

favored
for
low-power
por-
table
device
slide-in connections
for
use
in
a vari-
ety
of
applications where quick
and
easy
connec-
tions
and
disconnections
are
desired.
Examples
in-
clude
small
cards
that
slide
in

and
out
of
data
readers
or
small
handheld
devices
that
slide
into
cradles
and
docking
bays.
flat panel
Any
ofa
number
of
types
of
display
sys-
tems
that
are
narrower
and

flatter
than
traditional
CRT
displays.
These
may
be
special
flat
panel
CRTs,
gas
plasma
displays,
liquid
crystal
displays
(LCDs),
or
light
emitting
diode
displays
(LEDs).
Flat
panel
dis-
plays
are

especially
favored
on
mobile
systems,
such
as
computer
laptops.
flat panel CRT A
type
of
cathode-ray
tube
(CRT)
color
display
technology
in
which
the
electron
beams
are
aimed
parallel
to
the
front
of

the
display
device,
then
deflected
90
degrees
onto
the
viewing
surface.
This
configuration
permits
the
construction
ofa
much
flatter, smaller,
more
convenient display device.
While
this
technology
is
still
relatively
new
and
ex-

pensive,
the
bulkiness
of
traditional
CRTs
makes
the
flat
panel
CRT
commercially
attractive.
See
faceplate,
fiber
optic.
flat plate antennaAcommercial/industrial/military
satellite
communications
focusing
antenna
based
on
microcircuit
design.
It
is
similar
to

a
common
para-
bolic
antenna,
except
that
it
incorporates
a
series
of
concentric
rings
laid
over
a
transparent
sheet
to
cre-
ate
a
lens
that
can
be
used
to
redirect

signals.
flat rate service A
very
common
subscriber
billing
technique.
Flat
rates
usually
arise
in
services
where
the
overhead
of
keeping
track
of
many
different
types
and
quantities ofusage would cut into profits.
Flat
rate
services
are
also

attractive
to
many
subscribers,
as
they
know
in
advance
what
it
will
cost
and
don't
have
to
watch
the
clock
or
keep
track
of
usage.
In
computer
network
access
and

telephone
services,
flat
rate
billing
is
very
common.
Since
users
of
these
ser-
vices
vary
dramatically
in
time
of
access,
connect
times,
and
types
of
services
used
while
connected,
it

probably
is
more
economical
in
the
long
run
to
as-
sign
average
usage
fees
than
to
try
to
track
and
bill
widely
varying
usage.
Flat
rates
for
businesses
tend
to

exceed
those
for
residential
use
by
roughly
a
fac-
tor
of
three,
depending
on
the
type
of
service.
Local
phone
calls
in
many
areas
in
North
America
are
billed
on

a
flat
rate.
In
Europe
and
some
parts ofNorth
America,
per-call
charges
are
levied
instead
and
long-
distance
services
are
usually
billed
on
a per-call
ba-
sis.
The
newer
digital
cellular
technologies

sometimes
have
a
flat
rate
billing
option.
flat top
1.
Something
with
a
flat
surface
on
top,
as
a
flat-roofed
building
or
aircraft
carrier.
2.
The
portion
of
an
antenna
that

lies
horizontal.
flat top antenna An
antenna
that
has
two
or
more
parallel,
horizontally
strung
wires.
flatbed scannerA
type
of
desktop
scanner
that
per-
mits
the
object
to
be
scanned
to
be
placed
directly

on
the
scanning
surface;
the
object
lies
flat
and
doesn't
have
to
roll
through
a
drum
or
other
moving
mecha-
nism.
This
type
of
scanner
is
preferred
for
scanning
books

and
other
large
or
three-dimensional
objects.
flavor A
slang
term
for
type
or
model.
Programmers
Eif~~t:i.;~~~~i~ri;nr~r~~~~~;!~:~:~~a
patibility
issues.
The
distinction
is
somewhat
like
a
'dialect,'
in
languages,
or
a 'model'
in
a

type
of
car.
FLC
See
ferroelectric
liquid
crystals.
FLCD
ferroelectric
liquid
crystal
display.
See
ferro-
electric
liquid
crystal.
FLEA memory
flux
logic
element
array
memory.
The
whimsical acronym for a type of computer
memory
developed
by
RCA

in
the
early
1960s.
The
FLEA
was
created
photographically
and
was
capable
of storing
128
bits of information.
Its
processing
speed
was
100,000
items
per
second.
Fleming, John Ambrose (1849-1945) An
English
electrical engineer
who
investigated
the
Edison

ef-
fect
and
experimented
with
improvements
to
wire-
less
receivers
in
1904.
By
modifying
an
electron
bulb
so
that
it
incorporated
two
electrodes,
and
attaching
it
to
a
radio
receiving

system,
the
radio
waves
could
be
converted
to
direct
current
(DC).
Unfortunately,
this
new
diode
was
not
a significant
improvement
over
previous
electron
tubes,
but
it
was
important
in
the
evolution

towards
more
sophisticated
tubes
that
came
later.
The
most
important
of
these
was
the
tri-
ode
in
which
L.
de
Forest took
the
two-element
Fleming
tube
as
the
basis
for
the

invention of
the
Audion,
which
included
a controlling
grid
as
a
third
element.
See
two-electrode
vacuum
tube.
Fleming oscillation valve
An
electron
tube
devel-
oped
by
J.
A.
Fleming,
based
on
Edison's
work
with

electric
light
bulbs.
This
diode
tube
was
in
essence
a
two
element
rectifier.
While
it
did
not
achieve
the
practical
utility oflater
tubes,
it
led
to
the
develop-
ment
of
the

triode
by
Lee
de
Forest.
Fleming's rule
See
right-hand
rule.
flicker A characteristic of
display
devices,
such
as
cathode-ray
tubes
(CRTs),
in
which
the
scanning
of
the
screen
is
visible
to
the
human
eye

as
a
light-dark
flashing
flicker.
Flicker
can
result
from
a
number
of
causes,
including
the
quality
of
the
monitor,
the
mode
of
display
(interlace
or
noninterlace),
or
the
speed
of

the
screen
refresh
as
the
electron
beam
sweeps
the
screen. Generally, slower sweeps will appear
to
flicker
more,
as
do
interlace
screen
modes.
Apparent
flicker
is
eliminated
on
better
multiscan
monitors.
Most
individuals
can
comfortably

watch
displays that
are
refreshed
at
about
70
Hz
to
80
Hz;
above
that
level,
the
trade-off
in
cost
and
computing
is
not sufficient
to
justify the insignificant or
369
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary

nonexistent
improvement.
While
flickering
on
screens
may
be
uncomfortable
to
watch,
sometimes
an
interlaced
mode
has
a
prac-
tical
purpose,
as
when
an
NTSC-compatible
signal
is
being
generated
to
output

to
video.
See
cathode-
ray
tube,
frame,
interlace,
multiscan.
flip-flop
1.
Quick
reversal
of
direction
or
opinion.
2.
A
circuit
or
logic
state
that
can
assume
one
or
the
other

of
two
stable
states
(on/off,
high/low,
etc.).
A
trigger
circuit
or
toggle.
floating pointA
mathematical
representation
system
in
which
a
number
is
expressed
as
a product of a
bounded
number
(mantissa)
and
a
power

of
scale
fac-
tor
(exponent)
within
a
number
base
(e.g.,
base
10);
hence,
123.45
can
be
expressed
as
.12345
x
10
3
•
Floatingpointrefers
to
the
flexibility
inherent
in
plac-

ing
the
decimal
point
by
adjusting
the
exponent.
floating pointunit
FPU.
In
computers,
floating
point
math
coprocessing
chips
are
often
paired
with
cen-
tral
processing
units
(CPU
s)
to
carry
the

processing
load
of
the
math
calculations,
which
are
usually
cycle-
intensive,
thus
freeing
the
CPU
for
other
tasks.
floating selection
In
graphical
user
interfaces,
a
se-
lected
text
or
image
area

that
can
be
manipulated
and
moved
separately
from
its
background;
thus
it
appears
to
float
over
the
other
elements
on
the
screen.
Float-
ing
a
selected
region
is
useful
for

cut
and
paste,
drag
and
drop,
and
image
processing
applications.
flood
I.
To
inundate,
overflow,
or
cover
a
broad
area
all
at
once.
2.
In
scanning
and
printing
technologies,
flood

lamps
are
often
used
to
process
plates
and
pro-
vide
illumination
for
the
recording
of
images.
3.
To
inundate
with
data,
often
unintelligible,
as
an
incen-
diary
or
retaliatory
action.

4.
The
outpour of
vast
quantities
of
digitally
generated
infonnation.
See
core
dump,
data
mining.
flooding
I.
Overflowing,
inundating.
2.
In
networks,
a technique
of
sending many identical packets
through
various
routes
so
redundancy
increases

the
chances
of
the
data
reaching
its
destination.
3.
In
net-
works,
a
deliberate
act
of
vandalism
in
which
data
is
directed
toward
a
system,
or
an
email
address,
to

fill
the
hard
drive
space
or
tie
up
the
processor,
to
render
the
system
useless.
Users
caught
flooding
are
usu-
ally
denied
further
access
to
a
system.
See
core
dump,

mail
bombing.
FLOP
floating
point
operation.
Mathematical
ma-
nipulation
ofa
floating
point
number.
FLOPS
(Float-
ing
Point
Operations
per
Second)
is
often
used
to
describe
and
compare
microprocessor
speeds.
See

MFLOP.
floppy diskette, floppy disk A
thin,
compact,
por-
table,
flexible,
read/write,
random-access
data
stor-
age
medium
originally
encased
in
a
soft
protective
case
or,
later,
a
hard
protective
case.
Data
is
stored
and

modified
by
rearranging
magnetic
particles
on
the
surface
of
the
disk
and,
as
such,
the
disk
should
be
kept
away
from
magnetic
surfaces
to
reduce
risk
of
loss.
Generally,
magnetic

media
are
not
reliable
for
long-tenn
storage
(see
superparamagnetic).
floppy diskettedrive
FDD.
A
device
for
reading
and
writing
data
to
a
floppy
diskette
data
storage
medium
370
that
became
more
prevalent

in
the
early
1980s.
There
was
usually
one
floppy
drive
built
into
a
computer
and
sometimes a second external drive would
be
available
in
place
of a
more
expensive
hard
drive.
Prior
to
this, most consumer machines
used
tape

drives
to
store
data.
FLOPS
floating
point
operations
per
second.
Amea-
sure
of
the
speed
of
mathematical
computations.
See
FLOP.
flow
In
packet
networking,
a
sequence
ofpackets
with
the
same

source
and
destination
addresses
and
other
similar
characteristics.
The
detection
ofa
flow
by
various
routing
and
switching
mechanisms
can
trigger flow-based processing of
that
sequence
of
packets
to
improve
efficiency.
Flow
detection
may

also
include
marking
the
flow
with
a
label.
For
ex-
ample,
a
new
virtual
circuit
(VC)
may
be
set
up
for
a
packet
flow,
thus
removing
or
reducing
the
need

for
routing
until
the
end
of
the
flow
is
detected.
Flow
processing
is
a
means
of
handling
high-speed
data
through
systems
not
nonnally
capable
of
very
high
rates
of
packet

transmission.
The
bottleneck
is
the
overhead
in
managing
the
IP
datagrams
associ-
ated
with
the
packets.
Cut
Through
Routing,
devel-
oped
by
Ipsilon
(a
commercial
switch
vendor),
en-
ables significantly faster
IP

routing
by
detecting
classes
ofIP
flows
and
processing
them
accordingly.
When
processed
through
a
VC,
the
transmission
can
be
handled
by
a
switch
without
individual
routing.
The
signaling
between
IP

switches
is
handled
with
the
General
Switch
Management
Protocol
(GSMP)
and
the
Ipsilon
Flow
Management
Protocol
(IFMP).
See
General
Switch
Management
Protocol,
Ipsilon
Flow
Management
Protocol.
Flow
Attribute
Notification Protocol
FANP.

In
packet-switched
networks,
a
protocol
for
manage-
ment
of
cut-through
packet
fOIWarding
functions
be-
tween
neighbor
nodes.
F
ANP
indicates
mapping
be-
tween
adatalink
connection
and
a
packet
flow
to

the
neighbor
node,
and
it
helps
nodes
manage
the
map-
ping
infonnation.
This
allows
the
bypass
of
the
usual
Internet
Protocol
(IP)
packet
processing
by
allowing
routers
to
fOIWard
incoming

packets.
See
RFC
2129.
flow
chart
A
somewhat
standardized
diagrammatic
representation
of
processes,
procedures,
conditions,
and
directions
of
traffic
or
information
flow.
Flow
charts
employ
geometric
shapes,
symbols,
and
con-

necting
lines
to
indicate
the
relative
importance
and
relationships
of
the
concepts
being
illustrated.
Programmers
are
often
required
by
managers
to
pro-
vide
flow
charts
of
their
software
designs.
However,

many
argue
that
outlines
and
pseudocode
are
more
useful
in
representing
the
relationships
and
flow
within
a
software
program
than
conventional
flow
charts
because
of
the
lack
of
correspondence
between

human
interface
actions
and
the
looping
and
jump-
ing
structure
of
the
code
itself
(in
other
words,
the
order
and
frequency
with
which
the
user
interacts
with
the
software
rarely

corresponds
to
the
order
and
frequency
of
the
algorithms
and
procedures
that
en-
able
those
functions
to
be
executed).
Another
factor
complicating
the
application
of
traditional
manage-
© 2003 by CRC Press LLC
ment
flowcharts

to
the
programming
process
is
the
complexity
of
the
decision-making
points
in
a
pro-
gram
and
the
inability
to
predict
every
instance
and
sequence
of
events
that
the
user
might

take
in
a
so-
phisticated
program
with
many
options
(it
would
be
like
trying
to
chart
the
moves
in
a
chess
game
before
the
game
has
begun).
Code
usually
changes

many,
many
times
before
the
full
program
is
developed,
even
when
the
flow
rep-
resentation
stays
the
same.
Programming
is
a
rela-
tively
young
art
and
many
of
the
algorithms

are
still
being
invented
as
the
software
is
being
developed
and
cannot
be
known
in
advance,
before
the
problem
is
actually
solved.
Imagine
trying
to
flow
chart
the
high
school

course
selections
for
a four-year-old child
without
knowing
anything
in
advance
about
his
tal-
ents,
skills,
and
interests
and
then
you
can
understand
the
difficulty
of
flow
charting
a
software
program
before

it
is
written.
Thus,
flow
charts
are
best
seen
as
tools
for
conveying
to
management
and
co-workers
the
general
goals
and
structures
of a
project,
but
not
as
efficient
tools
for

developing
the
individual
com-
ponents of
the
computer algorithms themselves,
which
must
be
worked
out
as
they
are
encountered.
FLOW-MATIC
See
B-O.
Floyd-SteinbergA
dithering
algorithm,
i.e.,
a
means
of
creating
a
perceptual
tone

or
range
of
tones
by
in-
termixing
colors
related
to
those
tones
to
create
the
illusion of
more
colors. Dithering
is
one
way
of
stretching a limited palette
to
make
it
appear
as
though
there

are
colors
that
are
not
actually
available.
Dithering
works
best
with
dots
of
light
or
color
that
are
very
small,
too
small
for
the
human
eye
to
resolve.
In
the

Floyd-Steinberg
error
diffusion
algorithm,
the
error
between
the
approximate
output
value
ofa
pixel
and
the
actual
value
ofa
pixel
is
sequentially
diffused
to
its
near
neighbors.
See
dithering.
FLTSAT,
FLTSATCOM

The
U.S.
Naval
fleet
com-
munications
satellite
system
that
is
one
of
the
primary
U.S.
satellite
communications
systems
along
with
the
Defense
Satellite
Communications
System
(DSCS)
and the Air Force Satellite Communications
(AFSATCOM).
Together,
the

three systems
comprise
the Military Satellite Communications
(MILSATCOM)
system.
Control
of
the
systems
is
handled
through
the
Air
Force
Satellite
Control
Net-
work
(AFSCN).
FLTSATCOM
was
developed
in
the
early
1970s
to
provide
communications

for
seagoing
vessels,
air-
craft,
and
U.S.
military
ground
crews
worldwide.
In
addition
to
Naval
and
Air
Force
communications,
FLTSAT
was
designed
to
provide
fast
communica-
tions
between
the
U.S.

President
and
Commanding
Officers.
Transmissions
are
received
by
several
hundred
fixed
and
mobile
user
stations
on
sea,
air,
and
ground
ter-
minals
in
addition
to
Communication
Area
Master
Stations
(CAMS)

in
the
U.S.,
Guam,
and
Italy.
Chan-
nels
are
allocated
to
the
Navy,
Air
Force,
and
Com-
mand.
The
first
units
were
launched
in
the
late
1970s,
with
additional
units

added
to
the
system
in
the
1980s.
The
geographical
area
covered
by
the
near-geosyn-
chronous
equatorial
orbits
ranges
from
about
70
de-
grees
north
to
about
70
degress
south.
In

1991,
operational
control
of
satellite
programs
was
turned
over
to
the
3D
Satellite
Control
Squadron
(3
SCS)
which
became
the
3D
Space
Operations
Squad-
ron
(3
SOPS).
Then,
in
1996,

FLTSAT
constellations
were
turned
over
from
3
SOPS
to
the
Naval
Satellite
Operations
Center
in
California.
The
FLTSATCOM
Laboratory
has
a
computer
simu-
lation of
the
satellite
system
(minus
the
radio

fre-
quency
capabilities)
provided
by
The
Aerospace
Cor-
poration
that
gives
a
graphical
representation
of
the
satellite
and
its
operations.
When
fully
deployed,
a
FLTSAT
unit
resembles
a
trashcan
with

an
umbrella
on
one
end
(the
parabolic
antenna)
and
rectangular,
solar array'
elephant
ears'
protruding
from
the
central
body.
The
FLTSAT
sys-
tems
incorporate
a
number
of
antennas
in
different
wave

bands,
including
S-band,
UHF,
EHF,
and
SHF
(Super
High
Frequency)
radio
frequencies
and
have
an
operational
life
of
about
five
years.
They
weigh
approximately
one
to
two
tons
each
and

are
about
the
size
ofa
large
motorhome,
with
the
solar
panel
ears
extending
to
over
40
feet.
It
is
expected
that
the
UHF
Follow-On
(UFO)
system
will
eventually
supersede
the

FLTSAT
constellation.
fluorescent lampA
fluorescent
bulb
used
for
lamps
typically
consists
ofa
long
glass
tube
equipped
with
an
electrode
at
each
end,
with
specialized
vapor
and
gases
sealed
inside
the
tube.

When
electricity
passes
through
the
tube,
light
waves
are
emitted,
causing
phosphors
coated
on
the
inside
of
the
tube
to
glow.
Manufactured
since
the
late
1930s,
the
fluorescent
lamp
doesn't

use
a
filament
and
provides
more
light
than
an
incandescent
lamp
for
the
same
amount
of
current.
Since
less
current
is
required,
the
bulb
emits
less
heat.
Fluorescent
lamps
manufactured before

1978
may
contain
PCBs
in
the
ballasts
and
should
be
disposed
of
according
to
guidelines
for
PCB
disposal
to
avoid
contaminating
landfills
and
waterways.
flutter
1.
A
rapid,
repetitive,
agitated

back-and-forth
movement;
any
erratic
vibration
or
oscillation.
In
most
systems,
flutter
is
an
undesirable
characteristic
that
interferes
with
the
main
signal.
See
drift,
wow.
2.
Undesirable
phase
distortion
variations
that

may
result
from
more
than
one
frequency
transmitting
at
the
same
time.
3.
In
radio
terminology,
also
loosely
called
drift
and
wow.
flutter bridge A
device
to
measure
flutter
(undesir-
able
variations

from
a constant oscillation,
move-
ment,
or
signal).
It
is
used
for
testing
and
diagnostic
purposes
for
various
playback
devices
that
should
be
playing
at
a
constant
speed,
such
as
phonographs,
tape

recorders,
film
projectors,
or
disc
players.
flutter rate
The
speed
at
which
an
oscillating
body
moves
back
and
forth,
commonly
expressed
in
units
per
second
or
minute.
flux
1.
Stream,
continued

flow.
2.
An
expression
of
the
rate
oftransfer
across
or
through
a
unit
area
ofa
given
surface,
per
unit
of
time.
See
watt.
3.
A
sub-
stance
used
to
facilitate

the
fusing
of
materials,
as
the
use
of
rosin
in
soldering
or
welding.
4.
Magnetic
lines
371
© 2003 by CRC Press LLC