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I've seen and used patterns of holes (2, 4 and more) as a datum and it's pretty straight forward. It would seem to me you could also use a pattern of say 4 slots as a datum. Am I correct in this assumption? if so, how exactly would you show that on the drawing considering the way the slot is dimensioned. In the attached jpg which would be correct, Example A or Example B?
Can you post an image with higher resolution? Can't tell what's going on...
I upsized the text, is this more legible. I'm really just uncertain if I would add the same datum letter to each feature control frame for the slot dimensions or if they would be different datums.[IMG]http://www.engineersedge.com/engineering-forum/attachment.php?attachmentid=1890&stc=1[/IMG]
Figure 4-3 (f) in the Y14.5 standard shows an example of a single slot-type feature called out as a single datum. So it might be just like that, except that you want to add a "4X" in front. (Hoping you have access to that document?)
That's still somewhat unorthodox, but I guess as long as you reference the group datum with the "M" modifier in subsequent callouts then it would be OK.