Clarify the use of non-8-bit-channels in property textures about 3d-tiles HOT 1 OPEN

The feature ID texture channels property defines which channels are supposed to be combined (i.e. shifted and ORed together) to generate the feature ID. Beyond the question about non-8-bit channels (mentioned above), further clarifications that could be added:

Should there be a limit on the number of channels that can be combined for a feature ID?
For example, should it be possible to define the channels = [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17] (if an image format with this many channels existed)?

Should it be possible to use the same channel multiple times in order to generate the feature ID? For example, would channels = [0,1,0,1] be allowed?
At the first glance, this looks like it could not yield sensible IDs. But as some brainstorming (even though it is a bit of a stretch): People might want to use the bits like "tags". One could create one texture object with RGBA channels, and A always being 0. Then, one could create feature IDs with channels = [0,1,2,3] yielding 0x00BBGGRR, or with channels = [0,3,3,3] yielding 0x000000RR, which could be "disassembled" by the client, to see whether the center bits are BBGG or 0000...

from 3d-tiles.