QuakeC Structures and Objects
From Quake Wiki
Definition of structures and objects
It is often convenient, in C (or C++), to create new structures (or Objects, or record) to store a few related informations at the same place. For instance, you may wish to use a single structure to store all the ammo count of the player, and also the current selected weapon, since those informations are obviously related to each other.
Though both entity and vector are obviously structured types, it is impossible to create new structured types of that kind, in Quake-C. However, the entity type can be modified to suit some of your needs.