Version Found: MIG v1.0
Version Resolved: See (Xilinx Answer 58435)
All skew constraints tables include a note next to differential pair matching and a foot note stating "Do not consider package delay (P0) in skew calculation".
Also there is another "important" note which states that package delay must be taken into account.
Which is correct and why there is a difference for a small number of signals?
The User Guide notes are intended to convey that package delay does not have to be included when trace matching a single differential pair. (DQS_P, DQS_N and CK_P, CK_N)
The package skew on differential pairs is already accounted for when we defined the matching constraint.
(UG583) will be modified to reflect this more clearly.
11/5/15 - Initial Release