Datum as plane tangent to two cylindrical surfaces 2

[tw_0407]

I have a part with two partial cylindrical surfaces and I want to make a datum that is the plane tangent to the two surfaces, as the mating part has a flat surface that is seated up against them.

Part is similar to this example I mocked up:

And I want the datum to be tangent to both surfaces, like so:

Can I just sketch a line between them on a top-down view like in the above picture, and attach a datum to that?

 

[Burunduk]

"The reasoning for the targets in 7-58 is they are separate parts of a single datum which do not form a plane as opposed to being multiple contacts forming a single datum plane"

Multiple contacts forming a single datum plane could as well describe a datum targets application such as datum feature A in figure 7-60 (3 coplanar datum target areas). So that is hardly a criterion for the choice between the two types of datum feature designating symbols.

A much more likely criterion is: defined local contacts for datum targets vs. the entire surface/surfaces of a particular datum feature potentially intended to make contact with the simulator of the datum when the datum feature symbol is used without datum targets.