[Someone]

> the two-pronged idea in that file system, both a resource and a data component existed as pair. One metadata and one the file contents.

Application metadata describing what file types an application could open, what icons to use for those file types if they matched the application’s creator code was stored in the resource fork of the application, but file metadata never was stored in the resource fork. File types, creator codes, lock, invisible, bozo, etc. bits always were stored in the file system.

See for example the description of the MFS disk format at https://wiki.osdev.org/MFS#File_Directory_Blocks