egg syntax (intangible/trigger etc.)

1,Do these produce regular entries in a CollisionHandlerQueue, or do I need a special callback function for these?

How do they differ from regular … {Polyset descend}?
I mean, by default even the latter won’t prevent you going inside the collision mesh (the RRalph example stored the previous position, and put you back there).
Is there a technical difference between a {Polyset descend} and a {Polyset intangible}, or is it just a reminder for the programmer for intended use?

2, When I use Chicken to generate a collision octree, I have a lots of barriers in my egg, but I never got to make those egg to work (no collision appears in my collisionqueue, but without octree generation everything works fine). Does Chicken generate octree only for the mesh selected last, and not all selected ones?

Tags like “barrier” and whatnot are just egg macros. The definitions appear in your Config.prc file and look like this:

# The following define various kinds of collision geometry.  These
# mark the geometry at this level and below as invisible collision
# polygons, which can be used by Panda's collision system to detect
# collisions more optimally than regular visible polygons.
egg-object-type-barrier         <Collide> { Polyset descend }
egg-object-type-sphere          <Collide> { Sphere descend }
egg-object-type-invsphere       <Collide> { InvSphere descend }
egg-object-type-tube            <Collide> { Tube descend }

# As above, but these are flagged to be "intangible", so that they
# will trigger an event but not stop an object from passing through.
egg-object-type-trigger         <Collide> { Polyset descend intangible }
egg-object-type-trigger-sphere  <Collide> { Sphere descend intangible }

# "floor" and "dupefloor" define the nodes in question as floor
# polygons.  dupefloor means to duplicate the geometry first so that
# the same polygons serve both as visible geometry and as collision
# polygons.
egg-object-type-floor           <Collide> { Polyset descend level }
egg-object-type-dupefloor       <Collide> { Polyset keep descend level }

# "bubble" puts an invisible bubble around an object, but does not
# otherwise remove the geometry.
egg-object-type-bubble          <Collide> { Sphere keep descend }

# "ghost" turns off the normal collide bit that is set on visible
# geometry by default, so that if you are using visible geometry for
# collisions, this particular geometry will not be part of those
# collisions--it is ghostlike.
egg-object-type-ghost           <Scalar> collide-mask { 0 }

# "glow" is useful for halo effects and things of that ilk.  It
# renders the object in add mode instead of the normal opaque mode.
egg-object-type-glow            <Scalar> blend { add }