I am trying to find the specification of a reqif archive file (reqifz). Such an archive is used to transfer multiple reqif documents and "external" objects if i understand correctly. Can anyone point me to how such an archive is structured?
A reqifz file is a zip archive. It contains one or more .reqif files on the top level. The .reqif files in turn reference images and embedded objects. Those must be relative links, referencing other files in the archive. The referenced files can be in subfolders.
The ReqIF standard, including the latest 1.2 , does not dictate or even recommend a structure. The above is based on best practices and reflects how ReqIF-tools work.
Even the file extension .reqifz is not specified in the standard. It is a recommendation, based on a 3rd party Implementation Guide. You can validate .reqifz files (including links to embedded files) with the free validation tool from https://reqif.academy.