For information on converting to InterSystems IRIS, see the
InterSystems IRIS Adoption Guide
and the InterSystems IRIS In-Place Conversion Guide,
both available on the WRC Distributions page (login required).
Inherited description: Tests if the logical value %val, which is a string, is valid.
The validation is based on the class parameter settings used for the class attribute this data type is associated with.
In this case, MINLEN, MAXLEN, VALUELIST, and PATTERN.