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invalid tag

Category: ephemeral logic tag

Produces or tests for the value invalid.

Sample usage

<invalid> — produces the value invalid.

<invalid asdfjklasdfzxcv> — Tests the contents of the primary field and produces true since asdfjklasdfzxcv evaluates to invalid

Fields

Primary field

Category: vector field

Optional. The primary field may contain one or more values to test against.

Behavior

The invalid tag, when used without any field values, expresses the literal value invalid anywhere it is required.

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.