As you point out, there certainly are cases where metadata should not

be "passed through". Do you think adding an optional attribute to the

metadata element ( ) that would request data be

passed through would be helpful?


John,
There is certainly an advantage to allowing certain non-standard (NSmeta) metadata to pass through but the issue is complex and merits that the whole group consider it. Flagging NSmeta as pass through would help in some cases.
Another idea might be to have a tool to pass certain metadata from one dset or surface to another. This way, users who jump from one application to the next can simply reattach relevant NSmeta using some GIFTI 'refit' tool. One can also imagine allowing metadata matching by regexp methods to make such commands easy to run. So after a complicated sequence of processing, you can just add NSmeta using something like: gifti_tool -copy_missing_meta 'caret_*' source.gii target.gii . I'll encourage the rest of the group to chime in.


Regarding the surface normals, I whole heartedly agree with your suggestion that normals be kept out of the surface file. We actually compute the normals on the fly. But others might insist on having them and if that's the case we'll need to sort out how the coordinate transform relates to the normals. That's another detail the whole group should consider.

cheers,
ziad