ALTER TABLE PARAMIMPOSGUIA ADD IDCONTIMPDOC VARCHAR2(01) NULL
  CONSTRAINT CKC_IDCONTIMPDOC_PARAMIMPOGUIA CHECK (IDCONTIMPDOC IN ('S','N'))
/

ALTER TABLE DOCARRECADPAG ADD IDCONTABILIZA VARCHAR2(01) NULL
   CONSTRAINT CKC_IDCONTABILIZA_DOCARECADPAG CHECK (IDCONTABILIZA IN ('S','N',NULL))
/