string = text .size (0..64) policy_id = bytes ; no longer in text asset_name = bytes ; no longer in text and utf-8 files_details = { name : string, mediaType : string, src : string / [* string] } metadata_details = { name : string, image : string / [* string], ? mediaType : string, ? description : string / [* string], ? files : [* files_details] } label_metadata = { * policy_id => { * asset_name => metadata_details }, version: 2 } ; version 2 metadata = { 721 : uint => label_metadata }