Reference

Attaches one thing to another and adds Attach Flags to the attach_thing. Syntax:

 AttachThingToThingEx(attach_thing, base_thing, flags); 

flags: These are the Attach Flags to give to the attach_thing. These flags are optional because the attach_thing will be given 0x4 anyway.

AttachThingToThingEx() was probably created to avoid a more complicated system using SetThingAttachFlags(). That method works like this:

 AttachThingToThing(attach_thing, base_thing);
 SetThingAttachFlags(attach_thing, attach_flags);