Script: Zxxx

The ISO 15924 code Zxxx is used in language tagging to indicate that a document or text string has no written form — for example, purely spoken or signed content that has been transcribed in metadata without being rendered in any script, or audio recordings described in a database. It signals the absence of a script rather than an unknown or unspecified one and is used in BCP 47 language tags and other metadata frameworks to distinguish unwritten languages or unwritten forms of a language from written ones.