This is a transformation that can be applied to the substitution of content for both macros and macro parameters.
If the "delimiter" is not found on the end of the value being substituted then it is added. For example if a definition can contain a directory value with and without a trailing "\" then this trsnformation can optionally add the "\" character before you add a filename to it.
As a special case "?\" is converted to the correct slash for your operating system ("\" or "/" for unix).
;--- Define value --- #define SomeDir C:\SomeDir ;--- Use value --- File : <$SomeDir $$DEL:\>file.txt