An SPL file contains literal text to output, interspersed with code generator instructions.
Code generator instructions are enclosed in square brackets '[' and ']'. Multiple statements can be included in a bracket pair. Additional statements have to be separated by a new line or a colon ':'.
Valid examples are:
[$x = 42
$x = $x + 1]
[$x = 42: $x = $x + 1]
Text not enclosed by [ and ], is written directly to the current output file. If there is no current output file, the text is ignored (see Using files how to create an output file).
To output literal square brackets, escape them with a backslash: \[ and \]; to output a backslash use \\.
Comments inside an instruction block always begin with a ' character, and terminate on the next line, or at a block close character ].