SYSML17 — 9.3.2.9 What is InterfaceBlock?

9.3.2.9 What is InterfaceBlock? Where is description? Description is the same as constraint [1] text now.
InterfaceBlock is kind of Block, so, can it be used everywhere Block is used? e.g. part of the FullPort.

Constraint [2]. Does it mean Interface block can't have value properties and e.g. constraint properties?
Constaint [3] - does it mean "proxy ports" ? if so, it could be more clear text to say "InterfaceBlock can own proxy ports only"
constraint [4] - it must be constraint[4] for FullPort???

Improve the description

We propose to improve the Description sub-clause of 9.3.2.10 Interface Block by highlighting the definition first, then a bit about their usage.

Issues about the constraints have already been fixed