A rule is the most important construct in the grammar of openVALIDATION. It consists of a condition and an action. With a validation rule, the action is always an error message. The easiest way to express such a rule is a IF / THEN construct.
Selects the beginning of a rule and the next condition
Marks the beginning of an error message
Selects the start of a new linked AND condition
Selects the start of a new linked OR condition
Implicit Conditions / Alternative Rule Expression
MUST, SHOULD, HAVE, HAS
An indicator identifies an expression as a rule. The condition in such a MUST expression contains an Implicit Negation!
MUST NOT, MUSTN'T, SHOULD NOT, SHOULDN'T, HAS NOT, HASN'T, HAVE NOT, HAVEN'T
An indicator identifies an expression, as a rule
Relational operations always has a left and a right operand and the corresponding comparison operator.
IS, EQUAL, EQUALS
A relational operator '=' for numeric and string operands
ISN'T, IS NOT, NOT EQUAL, NOT EQUALS, NOT
A relational operator '!=' for numeric and string operands