setting a part of an antity as a vector

is there a way to set a certain part of an entity as a vector. for instance if the entity's pan is changed, then the vector is changed accordingly. i hope i have explained it well enough
Thanks

well, define a vector and set the valuse in a while loop?

It would be easier to set or update that vector in the player movement loop rather than have a new function just for that. However if it's something as simple as the character's facing then that should be accessed on it's own.

hmph, i dont think that i explained well enough. Umm.. it's for an equipping script. soo... basically i dont know how to keep a vector 'sticking' onto a certain part of an entity. For instance, keeping a vector sticking to an entity's arm, so when i 'equip' an item in the game, i can set the items' position as that vector, and the item goes onto the entity's say... arm.

I am not sure if i understand: maybee you mean "vec_for_vertex"?