> For the complete documentation index, see [llms.txt](https://docs.os.uk/os-downloads/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.os.uk/os-downloads/products/maps-and-imagery-portfolio/os-mastermap-topography-layer/release-notes/june-2026.md).

# June 2026

## OSMM Topography Layer product count

The following table contains product counts for this release of OSMM Topography Layer data. The dates shown are extraction dates, not release dates.

<table><thead><tr><th>OSMM Topography Layer</th><th width="276">Count on 23/04/2026 (Last Release)</th><th>Count on 04/06/2026 (This Release)</th></tr></thead><tbody><tr><td><strong>Total Feature Count</strong></td><td><strong>518 173 961</strong></td><td><strong>518 716 931</strong></td></tr><tr><td>Count of Topo Area</td><td>129 661 244</td><td>129 800 144</td></tr><tr><td>Count of Topo Line</td><td>357 302 510</td><td>357 689 858</td></tr><tr><td>Count of Topo Point</td><td>4 471 682</td><td>4 472 625</td></tr><tr><td>Count of Topo Bline</td><td>518 292</td><td>517 810</td></tr><tr><td>Count of Topo CartoSym</td><td>3 859 509</td><td>3 858 982</td></tr><tr><td>Count of Topo CartoTxt</td><td>22 360 724</td><td>22 377 512</td></tr><tr><td><strong>Total Count of Deletes</strong></td><td><strong>347 562</strong></td><td><strong>554 031</strong></td></tr><tr><td>Count of Topo Area deletions</td><td>64 297</td><td>107 977</td></tr><tr><td>Count of Topo Line deletions</td><td>235 690</td><td>407 755</td></tr><tr><td>Count of Topo Point deletions</td><td>1 197</td><td>1 801</td></tr><tr><td>Count of Topo Bline deletions</td><td>1 968</td><td>728</td></tr><tr><td>Count of Topo CartoSym deletions</td><td>2 541</td><td>2 767</td></tr><tr><td>Count of Topo CartoTxt deletions</td><td>41 869</td><td>33 003</td></tr><tr><td><strong>Total Count of Inserts</strong></td><td><strong>757 223</strong></td><td><strong>1 097 001</strong></td></tr><tr><td>Count of Topo Area inserts</td><td>168 092</td><td>246 877</td></tr><tr><td>Count of Topo Line inserts</td><td>525 019</td><td>795 103</td></tr><tr><td>Count of Topo Point inserts</td><td>1 771</td><td>2 744</td></tr><tr><td>Count of Topo Bline inserts</td><td>260</td><td>246</td></tr><tr><td>Count of Topo CartoSym inserts</td><td>1 666</td><td>2 240</td></tr><tr><td>Count of Topo CartoTxt inserts</td><td>60 415</td><td>49 791</td></tr><tr><td><strong>Total Count of Modifications</strong></td><td><strong>566 286</strong></td><td><strong>2 919 560</strong></td></tr><tr><td>Count of Topo Area Modifications</td><td>264 713</td><td>483 027</td></tr><tr><td>Count of Topo Line Modifications</td><td>264 101</td><td>2 408 940</td></tr><tr><td>Count of Topo Point Modifications</td><td>471</td><td>395</td></tr><tr><td>Count of Topo Bline Modifications</td><td>1 046</td><td>1 217</td></tr><tr><td>Count of Topo CartoSym Modifications</td><td>30</td><td>22</td></tr><tr><td>Count of Topo CartoTxt Modifications</td><td>35 925</td><td>25 959</td></tr><tr><td><strong>COU Size (bytes)</strong></td><td><strong>326 483 968</strong></td><td><strong>552 968 192</strong></td></tr></tbody></table>

## Changed TOIDs

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:

| TOID                 | Location (i.e. XY Coordinates) |
| -------------------- | ------------------------------ |
| 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           |

## Discrepancies <a href="#hlk115182660" id="hlk115182660"></a>

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.

## Next release

The next release of OS MasterMap Topography Layer is scheduled for **03 August 2026.**


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