Just noticed in checking my sustained displacements that most of my +Y restraints (specified with a 1/8" gap) have a -Y displacement of 1/8". What's up with that?

The answer is in your question.

You are seeing a -0.125" vertical displacement because you are specifying a 0.125" gap in your vertical restraint. Do not think of the gap as "horizontal gap", for that you would use a Guide with a specified gap. So the pipe is "falling" because you specified a gap between the bottom of pipe and the support.

In other words, when you specify a gap you are specifying a certain dimensional space between your pipe and the support in THAT specific direction (your case being in the Y-axis).

Please re-read my post. I specified a +Y restraint which, according to the CII manuals, restricts -Y movement and allows +Y movement up to any gap amount.

Please re-read my post.

Not only is it annoying to have to repeat myself on such a silly question when I already explained it clearly, but also you think you are right when your results clearly back me up... which makes it more annoying!

Quoted DIRECTLY from CII manual: "Orientation of the gap along the line of action of the restraint is accomplished via the sign on the restraint. The gap direction is opposite the direction of travel"

So sorry you're annoyed. So how would I model a guided shoe on a section of horizontal pipe with 1/8in gaps in the guided and vertical (up) directions? Are you saying I would need the following three restraint fields?

+Y
-Y Gap:1/8in
Guide Gap:1/8in

Yes you would need these three restraints.

When you specify a directional restraint (+Y for example), that specifies the direction of free movement. A gap added to this restraint acts in the direction opposite to the free movement.

Exactamente.

Thanks LT & Rich.

Rich, is there a functional reason for CII specifying gaps in this way? Meaning Gaps are in the opposite direction from the specified restraint direction? I ask because it would seem to me (granted limited experience) that gapping in the direction of allowed movement would lead to having to specify fewer restraints (by reflecting the common conditions).

Think of it this way: a gap acts against the restraint, permitting the specified amount of motion where otherwise the restraint would prevent that motion.