Quote - OK. This is starting to make sense now.

Now that I think about it, conforming clothes do two things: (1)They move, twist and bend with the base figure, and (2) they respond to the morphs of the base figure. You seem to make a distinction between conforming clothes and auto-conforming clothes. Is that what the difference is? Does conforming strictly mean responding to movement of the base figure while auto-conforming means responding to the base figure's morphs? Or am I reading too much into this?

Correct, that is it

Quote - So, back to the check boxes...

It looks like vendors can design their clothing to either auto-conform or to require the check boxes. The internal mechanics for how the clothes work may be very different but to the user the behavior should be identical (assuming that the clothing is "Conformed to...." the base figure and the "Include morphs when conforming" box is checked. Is that right?

Ideally they should be the same. But in practice, this is not always the case. For the checkboxes to work, the clothing has to be made with the exact names for all the morphs (I think external actor names, but I am not sure). For the autoconforming, the internal names have to be identical. If both are the same (internal and external), they should do the same. Except..... The FBM often do not work in autoconforming clothes, so the checkbox conforming is ignored, which does not matter because the autoconforming works. And there are some clever people again, which DO make FBMs work with autoconformingm but most clothing does not.

Quote - So how is the user supposed to know whether to check the box or not especially since "turning these features on in some cases breaks this"?

Here you get into the realm of compatibility. DS and pre Poser 8 do not have the checkboxes, so often autoconforming is used to remain compatible with these versions. How should the user know? Good question - I think the only way is to try the box for a clothing item when it does not fit. If it works for one item, it usually works for all the items in that set.

Is this a mess? Yes, in a certain way it is. On the other hand, you get used to it pretty quickly to checking the boxes on or off is not a big thing. Often the boxes are checked for P9 only items because the compatibility problem does not exist there.