June 2026
This release note provides information about the latest release of OS MasterMap (OSMM) Topography Layer, released to customers on 22 June 2026.
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This release note provides information about the latest release of OS MasterMap (OSMM) Topography Layer, released to customers on 22 June 2026.
The following table contains product counts for this release of OSMM Topography Layer data. The dates shown are extraction dates, not release dates.
Total Feature Count
518 173 961
518 716 931
Count of Topo Area
129 661 244
129 800 144
Count of Topo Line
357 302 510
357 689 858
Count of Topo Point
4 471 682
4 472 625
Count of Topo Bline
518 292
517 810
Count of Topo CartoSym
3 859 509
3 858 982
Count of Topo CartoTxt
22 360 724
22 377 512
Total Count of Deletes
347 562
554 031
Count of Topo Area deletions
64 297
107 977
Count of Topo Line deletions
235 690
407 755
Count of Topo Point deletions
1 197
1 801
Count of Topo Bline deletions
1 968
728
Count of Topo CartoSym deletions
2 541
2 767
Count of Topo CartoTxt deletions
41 869
33 003
Total Count of Inserts
757 223
1 097 001
Count of Topo Area inserts
168 092
246 877
Count of Topo Line inserts
525 019
795 103
Count of Topo Point inserts
1 771
2 744
Count of Topo Bline inserts
260
246
Count of Topo CartoSym inserts
1 666
2 240
Count of Topo CartoTxt inserts
60 415
49 791
Total Count of Modifications
566 286
2 919 560
Count of Topo Area Modifications
264 713
483 027
Count of Topo Line Modifications
264 101
2 408 940
Count of Topo Point Modifications
471
395
Count of Topo Bline Modifications
1 046
1 217
Count of Topo CartoSym Modifications
30
22
Count of Topo CartoTxt Modifications
35 925
25 959
COU Size (bytes)
326 483 968
552 968 192
Numerous TOIDs (Topographic Identifiers) have changed since the last refresh, resulting in a visual difference in the data. The list below shows a sample of changed TOIDs and their locations that you can use as 'lookup samples' to validate that your latest supply has updated correctly:
osgb1000000384062410
179839, 817668
osgb5000005352974816
298860.451, 206965.72
osgb5000005143395296
478103.497, 262235.611
osgb5000005191013959
211940.07, 900418.763
osgb5000005105988062
181505.908, 211436.228
osgb1000002577040403
372428.07, 523732.27
In this release 4 errors were detected, of which, 0 have existed since the previous refresh. These are all considered to be minor errors and there are no major errors present.
We aim to have all errors resolved prior to the next release as part of ongoing quality improvements.
The next release of OS MasterMap Topography Layer is scheduled for 03 August 2026.
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