How can I determine what version of Creative Suite created an FXG?
You can tell which version of Creative Suite created an FXG by looking using fmt=fxg. In the top of the s7fxg content, there is an attribute called s7:appVersion. If the value is 1.xxx, then it was created in CS4. If the value is 2.xxx, it was created in CS5/5.5 3.xxx indicates that it was created in CS6.