Trying to use a filename (as opposed to a module name) doesn't work on my Perl (5.005 on Linux). It throws a syntax error. The man page on use offers some insight as to why:

It is exactly equivalent to

    BEGIN { require Module; import Module LIST; }
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except that Module must be a bareword.

Therefore, to use use, the constants file must be a proper module ending in .pm, and the above use 'myIncludeFile.pl' (); syntax is a syntax error.

stephen