Inside the Repo, there is also associations.js file which provides associations between typesets and corresponding file name extensions & mime types.

jBinary uses those associations for loading data from external sources when typeset is not specified explicitly.

If you want your typeset to be associated with special file extensions or some mime-types, simply add entry into descriptors object in this file like:

var descriptors = {
  // ...
  tar: {
    extensions: ['tar'],
    mimeTypes: ['application/tar', 'application/x-tar', 'applicaton/x-gtar', 'multipart/x-tar']
  }
};