Control description categories: Column C | Column D (Landforms; Rock and boulders; Water and marsh; Vegetation; Man-made features; Special items) | Column E | Column F | Column G | Column H | Special instructions
Column D indicates the feature on which the control flag is placed. These are cross-referenced
to the ISOM 2017-2 (International Specification for Orienteering Maps) and ISSprOM 2019-2
(International Specification for Sprint Orienteering Maps) symbol or symbols used to represent
them (which are generally harmonised). Note that where a number is given it includes all symbols
beginning with that number (e.g. 509 indicates 509.1 & 509.2).
If a second control feature is required (i.e. for crossing; junction; between) then this must go in
column E. It is not permitted to place two symbols in Column D.
Rock and boulders (ISOM / ISSprOM section 3.2)
| Ref. | Symbol | Name | Description | ISOM/ ISSprOM |
|---|---|---|---|---|
| 2.1 |  | CLIFF, CRAG | A cliff or rock face. May be passable or impassable. | 201 202 |
| 2.2 |  | ROCK PILLAR | A high, natural rock projection. | 206 |
| 2.3 |  | CAVE | A hole in a rock face or hill side, often leading to underground workings. | 203 |
| 2.4 |  | BOULDER | A prominent free-standing block of rock or stone. | 204 205 |
| 2.5 |  | BOULDER FIELD | An area covered by so many boulders that they cannot be individually mapped. | 208 209 |
| 2.6 |  | BOLDER CLUSTER | A small distinct group of boulders so closely clustered together that they cannot be individually mapped. | 207 |
| 2.7 |  | STONY GROUND | An area covered with many small stones or rocks. | 210 211 212 |
| 2.8 |  | BARE ROCK | A runnable area of rock with no earth or vegetation cover. | 214 |
| 2.9 |  | NARROW PASSAGE | A gap between two cliffs or rock faces that face each other. | 201 202 |
| 2.10 |  | TRENCH | A rocky or artificial trench. | 215 |