Produces or tests for the value invalid.
<invalid>
— produces the value invalid.
Optional. The primary field may contain one or more values to test against. The invalid tag, when used without any field values, expresses the literal value When at least one primary field value is specified, the tag tests whether the value(s) are exactly the value invalid. Testing for invalid is often useful for validating a result produced with unreliable user input before it is passed back to the running program.<invalid asdfjklasdfzxcv>
— Tests the contents of the primary field
and produces true since asdfjklasdfzxcv
evaluates to
invalid
Fields
Primary field
Category: vector field
Behavior
invalid
anywhere it is required.