OPTCHARS
OPTCHARS is a list defining the characters the compiler/ linker command allows to specify an option (typically "-" or "/").
If some option characters can be used interchangeably on the command line, those characters are given without a separator. Otherwise, a comma is used for separation.
Examples:
OPTCHARS = - OPTCHARS = -,+ OPTCHARS = -/In the second example, some options start solely by "-" and some others solely by "+". In the third example, all options can start either with "-" or with "/" (as for example with Microsoft cl).