OS markings on ww2 british equipment

[WpgBinocular]

The VAOS catalogues are voluminous containing literally thousands of codings for practically all military equipment and parts used by the U.K. and Commonwealth armies (not navies). They were introduced about 1868 and were phased out upon with the introduction of NATO Stock Numbers in 1956. Attached is a typical cover page from a British 1940 VAOS Catalogue and an overview of the VAOS system written by Clive Elliott which unfortunately is no longer available on-line. Also see Clive Law’s “Without Warning, Canadian Sniper Equipment in the 20th Century” pages 54-55 and 81-86.

[rob love]

I'm not so sure about the Ordnance Stores being this OS abbreviation. For artillery parts, the prefix is FL, Tools and Accessories are CM, certain gauges are MC, and optical items are OS. There are others.
I am a believer that the initials mean something, and are not just random or added alphabetically.