farm league home run rule

Question
The batter's ball hit the top rail of the center field fence untouched by a defensive player and bounced back into the playing field.  Should this be a home run or a ground rule double?  If there is a rule that backs this up, please let me know which one it is.  We use the BPA Rulebook.  Thank you.

Answer
John,

This is typically covered by the ground rules at a particular field.  Many major league outfields have a yellow line somewhere along the fence that if a ball hits above, it is a homerun.  

If there is no line or ground rule for this field, I would say this ball is in play - no ground rule double, no home run.  Whatever the batter can get.

Hope this helps!

Brian