A message file is plain text, read line by line. Every line is one of three things:

• an empty line — blanks, a # comment, or nothing;
• a directive — a $ followed by a keyword: $MODULE, $LANGUAGE, $STRING, …;
• a line that belongs to the message above it — a parameter, a language header or a text line.

# greetings.msg — a complete message file
$MODULE greetings
$NAMESPACE app
$LANGUAGE en
$STRING ENABLE

$MESSAGE Welcome
@ user std::string const &
"Welcome, {$user}!"
[tr]
"Hoş geldin, {$user}!"

$MESSAGE Welcome opens a message; the @ line declares its parameter; the quoted lines are its text in English and — after the [tr] header — in Turkish. The next directive, or the end of the file, closes it.

Keywords and case

Directive and option keywords are case-insensitive: $MESSAGE, $message and $Message are the same, and so are ENABLE and enable. Everything you name — messages, parameters, classes, namespaces — keeps its case, because it becomes C++.

Where to go next

These pages are the syntax. What each directive does, and the C++ it produces, is the Reference Manual.