The operator isa is a binary operator that tests whether a given expression is of a particular type. The main purpose is to test the type of the data that is held in a field of type ANY.
testExpression isa typeSpecification
Do not include a datetime mask.
The logical expression resolves to true if testExpression matches the type identified in typeSpecification; and otherwise resolves to false.
Related reference
Arrays
Logical expressions
Operators and precedence