Thanks! This is the first time I've written the word out, I always abbreviate it OS

Actually, you were correct [1], jfk13 is mistaken, but it was an easy mistake to make.

[1] https://en.wikipedia.org/wiki/Ordnance_Survey

I corrected it in an edit. I originally spelled it Ordinance.

Ordnance literally means artillery; shells and bullets :)

Which is exactly how they got their name: the Ordnance Survey was the organisation responsible for generating accurate maps for the purposes of planning and executing artillery shoots.

To be precise, their original goal [0] was to map Scotland in the aftermath of the Jacobite rising of 1745, to to help the crown to subjugate the clans (as opposed to just lobbing arty fire at them).

[0] https://en.wikipedia.org/wiki/Ordnance_Survey#Origins

That actually makes more sense than "Ordinance Survey" :)

It could be the national government's legally authoritative survey :)