How to identify/demarcation 2 set of Multiple Identical Features

[Bryan.mys]

I am working on a drawing with a bunch of holes. Those holes were scattered around the product with another set of similar looking holes. How should I indicate which hole belongs to which set? (apart from dimensioning them on different view)

I was wondering if it is ok to use annotations "a1,a2, a3, a4, "b1, b2" to demarcate each set and where they are, then place "a1~a4" under the 4X XX.XX.

 

[Ryan6338]

Hole tables are a common way to achieve this. Most CAD software should be able to do it automatically. ISO 129 provides the following example of "Tabulated repeated features":

Ryan.