http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Ordnance survey national grid plans, scale 1:10,560. London
maps ; 45 x 45 cm., on sheets 73 x 49 cm., or smaller.
printed and published by the Director General of the Ordnance Survey.
"The Grid lines on this sheet are at 1 kilometre interval."
"The representation on this plan of a road, track or footpath is no evidence of the existence of a right of way."
Some sheets indicate "Revised" with dates.