Its how the game processes sound and text via the description.ext. The STRM values are linked to the stringtable file that you'll also find somewhere in the campaign folders. A stringtable is where the text for a mission is held. I never use them but that's because I only make missions in English, because I'm dumb. With a stringtable you can have text in numerous different languages, all accessed from one line in the stringtable, and the STRM bit in the description. A multi-lingual mission maker can have the titletext appear in either language depending on where the player is from. I'm not sure I've described it right but I'm sure someone will clarify.
The }; characters signify the end of a bit of information. These have caused many a crash to desktop. If you miss one out or make a mistake typing one, it'll wreck your description.ext so great care must be taken when dealing with them. What I mean is that you'll have to search for the error which can be a chore.
There's tons more info that the bright guys can give you but that's my interpretation of it.
If you want to know how to put sound into your mission here's a short tute,
Get Goldwave from here,
http://www.goldwave.com/release.htmlThen record your voice using Goldwave and a mic and then save it as .ogg. You don't need to download Goldwave actually but its a very good and handy program. Any .ogg will do. One from the campaign folder or single player missions folder will do fine.
Next create a new folder in the folder where your mission is. Call it sound. It will be created in the Flashpoint folder summit like this,
C:\Program Files\Codemasters\Operation Flashpoint\Users\yourname\missions\yourmissionname
Next you must create a Description file using the notepad or wordpad.
Save it as Description.ext. Where it says save as type: set it to All Files
In this notepad file put this,
class CfgSounds
{
sounds[] = {Yoursoundfilename };
class Yoursoundfilename
{
name = "Yoursoundfilename";
sound[] = {"Yoursoundfilename.ogg", db+20, 1.0};
titles[] =
{
0, $STRM_Yoursoundfilename
};
};
You can cut and paste that bit up there.
Save it.
If you've put everything in the right place then the file should appear in the editor. Just make a trigger and in the second page you can call it up from the same place as the BIS default sounds.
Hope that's in depth enough to help you.