> 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/august-2026.md).

# August 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="326">Count on 04/06/2026 (Last Release)</th><th>Count on 16/07/2026 (This Release)</th></tr></thead><tbody><tr><td><strong>Total Feature Count</strong></td><td><strong>518 716 931</strong></td><td><strong>519 342 087</strong></td></tr><tr><td>Count of Topo Area</td><td>129 800 144</td><td>129 958 160</td></tr><tr><td>Count of Topo Line</td><td>357 689 858</td><td>358 140 859</td></tr><tr><td>Count of Topo Point</td><td>4 472 625</td><td>4 473 894</td></tr><tr><td>Count of Topo Bline</td><td>517 810</td><td>517 322</td></tr><tr><td>Count of Topo CartoSym</td><td>3 858 982</td><td>3 858 766</td></tr><tr><td>Count of Topo CartoTxt</td><td>22 377 512</td><td>22 393 086</td></tr><tr><td><strong>Total Count of Deletes</strong></td><td><strong>554 031</strong></td><td><strong>756 720</strong></td></tr><tr><td>Count of Topo Area deletions</td><td>107 977</td><td>143 937</td></tr><tr><td>Count of Topo Line deletions</td><td>407 755</td><td>565 880</td></tr><tr><td>Count of Topo Point deletions</td><td>1 801</td><td>2 577</td></tr><tr><td>Count of Topo Bline deletions</td><td>728</td><td>1 289</td></tr><tr><td>Count of Topo CartoSym deletions</td><td>2 767</td><td>4 306</td></tr><tr><td>Count of Topo CartoTxt deletions</td><td>33 033</td><td>38 731</td></tr><tr><td><strong>Total Count of Inserts</strong></td><td><strong>1 097 001</strong></td><td><strong>1 381 876</strong></td></tr><tr><td>Count of Topo Area inserts</td><td>246 877</td><td>301 953</td></tr><tr><td>Count of Topo Line inserts</td><td>795 103</td><td>1 016 881</td></tr><tr><td>Count of Topo Point inserts</td><td>2 744</td><td>3 846</td></tr><tr><td>Count of Topo Bline inserts</td><td>246</td><td>801</td></tr><tr><td>Count of Topo CartoSym inserts</td><td>2 240</td><td>4 090</td></tr><tr><td>Count of Topo CartoTxt inserts</td><td>49 791</td><td>54 305</td></tr><tr><td><strong>Total Count of Modifications</strong></td><td><strong>2 919 560</strong></td><td><strong>2 087 450</strong></td></tr><tr><td>Count of Topo Area Modifications</td><td>483 027</td><td>683 458</td></tr><tr><td>Count of Topo Line Modifications</td><td>2 408 940</td><td>1 381 302</td></tr><tr><td>Count of Topo Point Modifications</td><td>395</td><td>527</td></tr><tr><td>Count of Topo Bline Modifications</td><td>1 217</td><td>1 090</td></tr><tr><td>Count of Topo CartoSym Modifications</td><td>22</td><td>29</td></tr><tr><td>Count of Topo CartoTxt Modifications</td><td>25 959</td><td>21 044</td></tr><tr><td><strong>COU Size (bytes)</strong></td><td><strong>552 968 192</strong></td><td><strong>579 604 480</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) |
| -------------------- | ------------------------------ |
| osgb1000000288707129 | 270982.824, 960152.554         |
| osgb5000005336030861 | 236484.655, 206357.086         |
| osgb1000000275442044 | 363684.85, 147552.82           |
| osgb5000005271762130 | 244956.788, 949673.599         |
| osgb5000005351687039 | 258258.382, 332031             |
| osgb5000005352509485 | 530782.585, 259576.42          |

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

In this release 0 errors were detected.

## Next release

The next release of OS MasterMap Topography Layer is scheduled for **14 September 2026.**


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