>At one point you say "precompiler" when I guess you mean "preprocessor"?

Ah, you're right! Fixed, thanks!

>Also I think the C preprocessor would be relatively unhelpful with the file format you explained in the post: As soon as you reached the first unmatched, unquoted apostrophe, cpp would assume it was inside a really long character literal and refuse to substitute any macros until the next apostrophe.

Oh, that's a good point. I'm not sure how Visual C++ does with it, but I just tried with gcc, and it falls over on an apostrophe:

    $ cat values.h 
    #define MAX_PASSPHRASE_MINIMUM 20

    $ cat example.mcp 
    SymbolicName=ERROR_BITLOCKER_PASSPHRASE_MINIMUM_TOO_LONG
    The BitLocker minimum passphrase length can't exceed MAX_PASSPHRASE_MINIMUM.

    $ gcc --version | head -n 1
    gcc (GCC) 14.3.0

    $ gcc --preprocess --language=c --no-line-commands --include=values.h example.mcp
    SymbolicName=ERROR_BITLOCKER_PASSPHRASE_MINIMUM_TOO_LONG
    example.mcp:2:44: warning: missing terminating ' character
        2 | The BitLocker minimum passphrase length can't exceed MAX_PASSPHRASE_MINIMUM.
          |                                            ^
    The BitLocker minimum passphrase length can't exceed MAX_PASSPHRASE_MINIMUM.