/* Look up ID in the vocabulary (ATAB) and return its "definition" (KTAB), or
* -1 if not found. If INIT is positive, this is an initialisation call setting
* up a keyword variable, and not finding it constitutes a bug. It also means
/* Look up ID in the vocabulary (ATAB) and return its "definition" (KTAB), or
* -1 if not found. If INIT is positive, this is an initialisation call setting
* up a keyword variable, and not finding it constitutes a bug. It also means