Code for uncoded script

The ISO 15924 code Zzzz (also represented in Unicode as Unknown) is used for characters that have not yet been assigned to a specific script, or whose script identity cannot be determined. In Unicode, characters in newly-encoded blocks may temporarily carry the Unknown classification before a definitive script assignment is made. The code is also used in language tagging to indicate that the script of a text is entirely undetermined or unidentifiable. It should not be confused with Zyyy (Common), which applies to characters that are intentionally script-neutral, or Zinh (Inherited), which applies to combining characters.