DCW data is the population data for the terrains. The DCW site here.
When you choose to download the data, select these items:
Here is the descriptions of the downloaded files. Most often its preferred to rename them to suit more human readable format, just in case you need to load only specific feature into Dem2Terrain.
|pppoint.e00||Labels (town/city/village names)|
There has been much talk on the forums about the China and Russian data being unreadable by our utils, well recently the China data became available and it reads just fine on Dem2Terrain v1.9 and now Zaggy fixed the last remaining Russian data, it works also without problems now. Check the Russian DCW data topics here and here.