# Conditional assembly

Sections of a source file may be assembled conditionally, only if certain conditions are true. The [ and ] (if and endif) directives are used to mark their start and finish; | provides an else construct. The syntax is:

``

    [ logical-expression
    ...code...
    |
    ...code...
    ]

Note that [, | and ] may not be the first character of a line. If the logical-expression is true, the section will be assembled; if it is false, the second piece of code, the beginning of which is marked by | and the end of which is marked by ], will be assembled instead. Lines of code skipped during conditional assembly will not be listed unless the assembler is switched from its default TERSE mode by the -NOTERSE command-line switch.

The directives IF, ELSE and ENDIF may be used instead of [, | and ] respectively.