Glossary

This is a glossary of various terms used throughout the site. Many of these are specific to the America Online environment.

A

ACK

See Acknowledgement

ACK Packet

A specific type of P3 packet used to communicate acknowledgement information.

Acknowledgment

When either a client or host transmits information to the other side that acknowledges receipt of one or more P3 DATA packets. This can be done with ACK packets or via piggybacking.

Atom

A command in FDO

C

Client

Software that runs an end-user's computer. Communicates with a host.

CRC

See Cyclic Redundancy Check

Cyclic Redundancy Check

An error-detecting code computed over various packet fields.

D

DATA Packet

A specific type of P3 packet used to communicate tokens between client and host.

DOD

See Download On Demand

Download On Demand

A mechanism for updating artwork, forms, and on the client.

F

FDO

The client command language. Typically used for creating forms displayed by the client, however also includes additional functionality (such as logging off the client.)

Form

A window in the client.

Form Definition Opcode

See FDO

Form Definition Operator

See FDO

G

GID

See Global ID

Global ID

A unique 32-bit numeric identifier. Similar in intent to a GUID or UUID, though with a much smaller range.

Gratis ACK

An ACK packet sent when a specific number of packets have been received and no acknowledgements has been sent by piggybacking.

H

Host

Server software that clients communicate with.

I

IM

Instant Message

IP

Information Producer, or Internet Protocol (which one depends on the context)

P

P3

The underlying protocol used to communicate between client and host. P3 is an acronym for Playnet Proprietary Protocol.

Piggybacking

Using an outbound packetsto transmit acknowledgement information. This avoids the need to transmit a separate ACK packet, and thereby reduces the number of packets transmitted.

S

Sliding Window

A method of feedback-based flow control used by P3 to control the rate at which packets are sent back and forth.

T

TOD

See Tool On Demand

Token

A message sent between client and host. The first two bytes identify the type of token, and the rest of the bytes are the token data.

Tool

A component of the client. Implemented as a DLL with specific exports.

Tool On Demand

A mechanism for updating client tools.