Drawing Dimensions

[Chucketn]

I know this has been posted before, but I can’t remember where.
I’m studying plans for my next engine project, one of Elmer’s’ Wobblers. The drawings have dimensions like Ø3H7, or Ø12P7. I forgot to save a link or print the page that explained these dimentions. Can anyone help?
Chuck in E. TN

 

[Chucketn]

Thanks for the quick responses. It was right there on the site I downloaded the plans from.

Chuck in E. TN

 

[Weldfab]

And I still think the system sucks.

I agree with Paddy! Sometimes I get so confused with some of the prints I deal with. But on the other hand it does protect the customer when it comes to parts being out of spec.