OS Master Map - Custodianship of The Data

Custodianship of The Data

Although branded like a commercial product, OS MasterMap is in fact the UK’s most complete, accurate and up-to-date geographic record. By moving to purely digital media for mapping, Ordnance Survey brings upon itself the responsibility of being the sole mandatory custodian of Great Britain's official maps. Previously, by virtue of being a publication on paper, a copy of every edition of every paper map published by Ordnance Survey would have been deposited, by law, with each of the six legal deposit libraries in the UK. Although there is no such law in place for digital maps, the Ordnance Survey makes annual 'snapshots' of the data and voluntarily deposits with the legal deposit libraries:

If you are not a licensee and wish to view and undertake limited copying of historic versions of OS MasterMap data, then you may do so at one of the six Legal Deposit Libraries that hold annual 'snapshots' of large-scale Ordnance Survey data, which Ordnance Survey voluntarily deposits by Agreement with these Libraries. The data may only be accessed within the premises of one of these Libraries, and views and prints made from the data may only be used for purposes included within the exceptions to the Copyright Designs and Patents Act 1988.

— Ordnance Survey website (Feb 2009)

The data, like any other, is susceptible to all the problems of computer data storage and digital preservation, for example: data corruption; the question of how often to take snapshots of the data (i.e. should every edit be recorded?); access to old versions of the data; practicable access to old versions of the data (after format changes, will new software be able to read old data?).