The $IF and $SET directives allow for partial compilation of a source file based on the states of software switches. Ten software switches (0 through 9) can be indepedently changed between binary states ("on" or "off") using the $SET directive. Sections of the source program can then be processed or skipped, depending on the state of any one or a combination of switches used in the $IF directive.
$SET Format
$SET [Xn={ ON } [, Xr={ ON }]]
{ OFF} { OFF}
where:
"Xn" and "Xr" are software switches.
n and r are integers in the range of 0 to 9.
All switches are "OFF" by default.
When the $SET directive is used by itself, it sets all switches to "OFF".
$IF Format
$IF [ Xn={ ON } ]
{ OFF}
where:
"Xn" is a software switch.
When the $IF directive is used by itself, it evaluates to true and any following program source is processed.
An $IF directive always ends the influence of any preceding $IF directive.