$INCLUDEONCE

The $INCLUDEONCE metacommand, when placed in include files, prevents that the file's contents can be injected multiple times into a program.

Syntax

This metacommand does not require a comment ' or REM before it.
It can be placed everywhere in an include file, but must be the only thing in the line, hence no additional whitespace or comments.
If placed in the main program, $INCLUDEONCE does nothing and is simply ignored without error.
$INCLUDEONCE will not work if placed inside pre-compiler $IF..$ELSE...$END IF blocks.