[Zope] Allowed SQL statements for ZSQL

Hi all, I'm looking for the SQL grammar, which is allowed/supported by ZSQL. E.g. the point is, how does ZSQL support sql-transaction expressions. E.g. "select NOW()" is a legal expression for MySQL, but causes a parse-error in ZSQL. There seems to be a "standard" inclusion of a limit clause within ZSQL for security and/or overflow reasons. Does anybody know the grammar? Are there considerations to suit or extend the grammar? Thanks Andreas