The “Position” of proximal locks refers to:
There are four characteristics or determinants of proximal locks:

Position.
Translation.
Depth.
Occlusogingival orientation.


Position refers to the axiofacial and axiolingual line angles of initial tooth preparation (0.2 mm axial to DEJ). It is important to note that the retention locks should be placed 0.2 mm inside the DEJ, regardless of the depth of the axial walls and axial line angles.
Translation refers to the direction of movement of the axis of the bur. 
Depth refers to the extent of translation (i.e., 0.5 mm at gingival floor level). 
Occlusogingival orientation refers to the tilt of the No. 169L bur, which dictates the occlusal height of the lock, given a constant depth.

Reference: Sturdevant operative dentistry. 4th edition, Page No:705
Direction of movement of the axis of the bur
The occlusal height of the lock, given a constant depth
The axiofacial and axiolingual line angles of initial tooth preparation
The extent of translation