Some more pointers on the config.cpp issues
Naming your addon: use an OFPEC tag
I cannot stress this enough. Register "PDOG" or "PDOGG" as your OFPEC tag and name your addon accordingly. This way, it wont collide with someone elses USP.
Suggestions for the addon name: PDOG_USPTactical or PDOGG_USPTactical
JAM compatibility
You do it just like Rasta described above. More to the point, the non-silenced version of your usp would have this as its magazines definition:
magazines[]={JAM_Mk23mag};
whereas the silenced one would use
magazines[]={JAM_Mk23SDmag};
One can imagine an USP variant that can take both kinds of ammunition, and it would have
magazines[]={JAM_Mk23mag, JAM_Mk23SDmag};
Declaring the addon dependencies
This is not an option - its a neccessity. Period. It is VERY important, and not only for MP play. Declaring the dependencies correctly will allow your USP addon to be used in mod folders and on dedicated servers without any problems. Failing to declare the dependencies will cause problems, even in SP. There really are no ifs and buts about it. Here's how the CfgPatches part of your addon might look:
class CfgPatches
{
class PDOG_USPTactical
{
units[]={};
weapons[]={PDOG_USP, PDOG_USPSD};
requiredVersion=1.85;
requiredAddons[]={BIS_Resistance, JAM_Magazines};
};
};
Two important things here: one is that the ability to declare addon dependencies came with OFP 1.85 (well, technically it was 1.82 but that was never released to us customers). The second is the list of actual addons your USP addon depend on. Note that what one declares there is not the name of the magazines from JAM2, but the encompassing addon class name. Hence, JAM_Magazines. The second one must be there for two reasons. One is that you will be using the CZ75 optics and that comes from Res/Addons/O.pbo. O.pbo is the addon that defines BIS_Resistance in it.
Secondly, it has to be there because JAM_Magazines depend on it. You see, one has to declare the whole dependency chain for one's addon, so even if you didn't use anything from O.pbo, you'd still need to have it there. This is because JAM_Magazines does use things from O.pbo/BIS_Resistance.
If you decide to add a couple of USP-sporting soldiers (a good idea), the units[] part will have to have these guys listed too, of course.
Good luck with your USP addon!