Language file compilation does not handle % as documented
When using the GemStone error message compiler in the process of
translating error messages, the %% is documented, in the SAG pG-7,
to print the % character.
This does not work correctly; after compiling, when the message
is invoked, the resulting error message will not include the %,
and the character following the %% in the source string will be
Instead of using %% for a percent sign, use \%\%