Condition types:

**Relation:** `identifier {= | > | < | >= | <= | NOT =} {identifier | literal}` - **Class:** `identifier IS [NOT] {NUMERIC | ALPHABETIC | ALPHABETIC-LOWER | ALPHABETIC-UPPER | class-name}` - **Condition-name:** `condition-name` (level 88) - **Sign:** `identifier IS [NOT] {POSITIVE | NEGATIVE | ZERO}