What are all the valid SystemCapabilities keys possible usually generated by Xcode?

I do not use Xcode to build my IPA. I tried searching apple documentation, but I cannot find what the key values are for all possible system capabilities. In order to not be lazy, I also tried to archive a project with these capabilities turned on, and searched through the IPA, but cannot find where Xcode6 is hiding these entitlements.

For users using Xcode6 these are the capabilities listed here

enter image description here

Since I generate my IPA manually, I need to know what these keys are in order to match the capabilities set on my App Identifier.

UPDATED

Here are the key values, they were actually in the project.pbxproj file, thanks for the help @colinta

SystemCapabilities = {
  com.apple.ApplicationGroups.iOS = {
    enabled = 1;
  };
  com.apple.BackgroundModes = {
    enabled = 1;
  };
  com.apple.DataProtection = {
    enabled = 1;
  };
  com.apple.GameCenter = {
    enabled = 1;
  };
  com.apple.HealthKit = {
    enabled = 1;
  };
  com.apple.HomeKit = {
    enabled = 1;
  };
  com.apple.InAppPurchase = {
    enabled = 1;
  };
  com.apple.InterAppAudio = {
    enabled = 1;
  };
  com.apple.Keychain = {
    enabled = 1;
  };
  com.apple.Maps.iOS = {
    enabled = 1;
  };
  com.apple.OMC = {
    enabled = 1;
  };
  com.apple.Passbook = {
    enabled = 1;
  };
  com.apple.SafariKeychain = {
    enabled = 1;
  };
  com.apple.VPNLite = {
    enabled = 1;
  };
  com.apple.WAC = {
    enabled = 1;
  };
  com.apple.iCloud = {
    enabled = 1;
  };
};

Solution

Your screenshot gave me an idea - check the diff of the project.pbxproj file! Came up with this:

+ SystemCapabilities = {
+   com.apple.GameCenter = {
+     enabled = 1;
+   };
+   com.apple.InAppPurchase = {
+     enabled = 1;
+   };
+ };

HTH