I have a question about what exporters should do with 'problems'.

Two examples which illustrate a problem:

1. Export selected. Choose a skin only. Skin relies on a number of bones to control it but these are not selected. What is the policy in this case?
Should those bones be forced for output because they are dependencies?

2. Export all; exports all non-hidden nodes. Skin is visible, but one or more bones which the skin relies on are hidden so would not normally be exported. Should these be forced for output because they are dependencies?

In the collada specification it describes what an exporter should/may support, but doesn't give policies on what should happen in the cases like these. So what should be done so that the action of exporters is consistent?