Plain English Meaning

A small sign placed right beside the red 'hold short' sign that tells you which taxiway you are sitting on while you wait. The two signs are mounted together so you can read them at a glance.

Full Definition

A black square sign with a yellow letter and yellow border (e.g., 'A') placed immediately next to a runway holding position sign, indicating the name of the taxiway on which the aircraft is currently positioned at the hold-short line.

Context Anchor

Seen on airport taxiways, especially near runway holding positions where pilots must confirm both their location and the instruction shown by the sign.

Derivation

Collocated' comes from Latin 'com-' (together) and 'locare' (to place) — literally 'placed together'. In this context it simply means the location sign is mounted next to the holding sign so reads them as a pair.