Terms
=====

Parts between < and > are mandatory. They will never contain white space and
thus can be mentioned as words.

Parts between [ and ] are optional. It can be one word, several words, or even
missing.

White space can be a space or Tab character. New line and carriage return are
not considered as white space.

<MID> is a message ID. It can contain alphanumeric characters (must match the
regular expression [a-zA-Z0-9]+), except for server messages which are not
generated in response to a client request, which begins with a dot (.).

<RESPONSE CODE> is similar to HTTP Status codes. The first digit depends on
the generator module. 0 is for the messages generated by RPGServ core; 1 is
for messages generated by RPG System modules. Other numbers are currently
reserved for future use. The second digit is the message level: 0 are
informational, or success messages; 1 are warnings, which are recoverable,
while 2 is for errors. 3 indicates server-side system failure, and is always
followed by a disconnect. 8-9 are two-level debug messages. 4-7 are currently
reserved for future use.

Client side
===========

<MID> <MESSAGE SIZE> <COMMAND> [ARGUMENTS]

MESSAGE SIZE contains the length of the whole message. Although white space
characters are ignored during message parsing, MESSAGE SIZE must include the
length of these characters, either.

COMMAND is the command itself.

ARGUMENTS are the (optional) command arguments. Arguments are case sensitive.
Each word in ARGUMENTS is a separate argument, white space and newline is
ignored between them, except the argument is wrapped between two " or '
characters. These two have identical meaning, but can not be swapped. To put a
plain wrapper character in a wrapped text, prefix it with a backslash.

Server side
===========

<MID> <RESPONSE CODE> <PIECE-NR> <PIECE-SIZE> <MESSAGE-CHUNK>

PIECE-NR is the packet number for the given message. Every message is divided
into packets based on the server side settings. Messages that fit in one
packet are sent with this field set to 0. Longer messages, or messages that
are generated over time and pieces can be sent meanwhile are numbered from 1.
The last piece of message for a given MID is always marked as LAST in the
PIECE-NR field.

PIECE-SIZE is the size of the current piece in bytes.

MESSAGE-CHUNK contains the message itself, or the chunk transmitted in this
packet. The message or message chunk doesn't have a trailing character, like a
newline.