Category

The Category operation consumes one character and tests it against a Unicode (or RegExp-specific) category. Depending on the first argument the result is used normally or negated.

; Category example: match an uppercase letter

CATEGORY &Lu
MATCH

Syntax

If you prefix the operation with the Not modifier, it negates it’s meaning. If you prefix the operation with the Assert modifier, the operation is testing the current character without consuming it.

CATEGORY &<category>
NOT CATEGORY &<category>
ASSERT CATEGORY &<category>
NOT ASSERT CATEGORY &<category>