[-z-]: Actually, the _v1r1 in the bsp name was not the originally intended way.
_v1r1.pk3 is meant to be compatible with _v1r2.pk3 and _v1r3.pk3, etc., and the BSP would be called _v1.bsp. That results in the map not being loaded or downloaded twice in the same game session.
When doing an incompatible change to the map, you start with a new major version: _v2r1.pk3, _v2r2.pk3, etc.
Compatible changes include:
- mapinfo changes
- entity changes (including light entities), except for misc_model
- texture or skybox changes
- shader changes
Incompatible changes are:
- changes of brushes
- changes of misc_model entities
- scaling the map
That way, unnecessary redownloading of the map is minimized, as the client does not need the mapinfo, the entities, and as texture or shader changes are minor and the map works with the old ones just as well. If you do that, the old map will be used when already loaded, but slowly phased out (it won't load the old one from dlcache, but redownload it then).
That is especially useful if you notice you made a mistake, and release a next update soon - that way, less people have the buggy version.
If you have no idea about what is compatible and what not, call the bsp file _v1r1.bsp etc. to be safe. But this will cause unnecessary downloading.
1. Open Notepad
2. Paste: ÿþMSMSMS
3. Save
4. Open the file in Notepad again
You can vary the number of "MS", so you can clearly see it's MS which is causing it.