Presence of a modifying symbol CF (Contacting Feature) in the feature control frame implies that some portions of datum feature are used to simulate datum and contacting features should be specified on the drawing.
ISO 5459:
In an example below:
“, the datum A with modifier [CF] is a set of two...
The parallelism tolerance is correct - it controls the orientation of the top (sharp edge) of V-shaped feature with respect to datum A.
That edge must be between two planes which are .005 apart - say, if you place this part face -A- down on a surface plate and indicate the top edge around, the...
Chez311 - yours is a great example from the standard of how to utilize these features as datum.
ISO 5459, Annex C illustrates association methods for creating datums from datum features.
I thought the confusion was in questioning how can the profile of a surface be a datum feature?
Using...
Datum Feature Symbol (Datum Indicator as it is know in ISO) can be attached to feature control frame. It indicates that a datum feature is the feature controlled by the geometric tolerance.
In your first image the datum feature A is the area between C and D defined by true profile (Radius 26.5)...
