Dear everyone

I have some Ordnance Survey series indexes from the 1940s, for one inch,
half-inch and quarter inch OS maps, as well as some later indexes for other
OS series maps.

On the GSGS 3908 index for the one inch maps of Scotland it has O.R. 1209
printed at the top. At first I thought this might be a revision code as some
other map indexes have similar codes, such as O.R.4050 (another 1" to 1 mile
Scotland series index), O.R.4048 (1" to 1 mile Ireland index) and O.R.4049
(1" to 1 mile, England & Wales index). However at the bottom of this
Scotland index is 2052/12/41 LR. which I know to be a revision code.

It may be that there were two revision codes. Does any one know, as I am
currently cataloguing the indexes and I am not sure where to put the
numbers? Has sheet indexes such as these been written about in articles or
books, by the Charles Close Society or others?

Kind regards

Timothy Langner