Compaq TA1000 Reference Manual page 17

2-4 Compaq TA1000 Tape Drive Array Reference Guide
3. If necessary, loosen the three screws in the middle of the mounting
bracket to adjust the length of the bracket to fit your rack.
4. For square-hole racks only: Position the left mounting bracket 1 just
behind the front vertical rail, aligning the middle two mounting bracket
holes with the rail holes previously marked using the template. Be sure
the alignment clip flanges are positioned within the mounting rail square
holes.
1
Figure 2-3. Square-hole rack bracket alignment