U.S. Patent No. 8,402,115, directed to interactive links.

Incorporation by reference was alleged to satisfy the specific reference needed for a priority claim (pages 3).  The priority claim, in its own and first section of the specification, is to a prior utility (parent), but not to the prior grandparent or even more prior provisional application (pages 3-4).  The provisional is mentioned in a following cross reference to related documents section, which includes “priority is herewith claimed” language (page 5).  The prior parent properly claimed priority to the grandparent application and the provisional (page 5).  The PTO initially indicated priority to both the parent and provisional but mailed a corrected filing receipt prior to issuance indicating priority to the parent only (page 6).  35 U.S.C. §120 requires a “specific reference to the earlier filed application” for a copending application with §119 having a similar requirement for provisionals (pages 9-10).  The PTO regulations require the claim to be in the first sentence (pages 10-11).  The incorporation by reference of the parent application, with its correct claim for priority to the grandparent and provisional, fails as the specification of the patent at issue does not have a specific reference to the intervening grandparent or the provisional (pages 11-12).  The specific reference is not a mere technical requirement, but serves a public notice purpose (pages 12-13).  The incorporation by reference was general without detailing that the priority claim as being incorporated (pages 15-16).  The “essential” and “non-essential” nature of incorporated materials is, per MPEP, for §112 material, not for priority claims (pages 17-19).  Thus, the earlier filed PCT with the same specification is prior art (pages 3 and 20). 

Hindsight: Reliance on the mentality that “clerical” errors will not hurt a patent can be devastating.  The MPEP, CFR, and statutory requirements should be followed.  The change to the filing receipt was not challenged.  Attempting to correct after receiving the corrected filing receipt may have helped.  Details may matter.  For a priority claim, the entire chain of title, including the serial numbers, filing dates, relationships, and express claims for priority, should be expressed in the first sentence.