Which Result Content types are valid for discovery and which are valid for non-discovery retrieves?

The oneM2M specs (various versions) seem to be very unclear about what should be returned for various combinations of rcn & fu flags.

can some please clarify? possibly with pointers to spec sections?

for example:

In TS-0001 v2.27, section 8.1.2, the only 'Result Content' type description that mentions discovery is child-resource-references which says "This option can be used within the context of resource discovery mechanisms". Does this imply that none of the other Result Content types can be used within the context of resource discovery mechanisms, since their descriptions do not explicitly allow this?

If that is the case, then why does TS-0004, section (7.2.1.2) talk about both URIList and resourceRefList in Discovery responses? These two things seem to be in conflict.

Solution

as per my discussion with @andreas-kraft, the answer is:

attributes
attributes+child-resources
attributes+child-resource-references
child-resource-references (default)
original-resource
child-resources
semantic-content