add new key-value tags for the item. Note that there can be multiple values for a tag.
public static bool AddItemKeyValueTag(UGCUpdateHandle_t handle, string pchKey, string pchValue) { InteropHelp.TestIfAvailableClient(); using (var pchKey2 = new InteropHelp.UTF8StringHandle(pchKey)) using (var pchValue2 = new InteropHelp.UTF8StringHandle(pchValue)) { return NativeMethods.ISteamUGC_AddItemKeyValueTag(handle, pchKey2, pchValue2); } }