doc.FAQ.WhatDoesUseSPACEForSQL_IDENTIFIER_QUOTE_CHARDo

This is a Progress SQL-89 specific option which if set the driver returns " " rather than "" to represent this database does not have a quoted identifier character. The ODBC specification says that " " is what should be returned but some applications (like Crystal Reports) interpret this response as meaning the quoted identifier character is a "space", which obviously does not make sense and fails, as they are expecting "" to be returned hence this need for this option.