A locale map is filtered by its own tag ranges and carries no Criteria: matching by localised text attaches
at the enclosing collection through an Expression, not on the map.
True if value is a non-empty plain object whose keys are all RFC 4647 basic language ranges and whose
entries are all Atomic value templates; false otherwise
Checks if a value is a Locale template.
A locale map is filtered by its own tag ranges and carries no Criteria: matching by localised text attaches at the enclosing collection through an Expression, not on the map.