CAFC test: whether a reasonable examiner would be so befuddled

The issue in the case pertained to "incorporation by reference" of an application
filed on the same day, at a time when the application number of the incorporated
reference was not known.

Within the CAFC decision in Harari v Hollmer :

In other words, the relevant inquiry is whether a
reasonable examiner would be so befuddled by the language of the original disclosure,
despite the explanation provided in the transmittal and preliminary amendment, that he
could not determine what document was intended to be incorporated by reference. See
In re Fouche, 439 F.2d 1237, 1239 (CCPA 1971); see also 37 C.F.R. § 1.57(g)(2).

Of the practical question of "how to update" previously incomplete information (e.g., a
previously unknown application number), the CAFC notes:

It is not inappropriate for an application to identify for the purposes of
incorporation by reference a co-pending application by title, inventors, and a context-
specific filing date, where such information is sufficient to identify the application at the
time the information is presented. 37 C.F.R. § 1.57(g)(2). It is not new matter, and
indeed it is strongly encouraged, to later amend the identifying language to recite a
serial number and filing date, when that information becomes available. Id.; see also
Scarring Corp. v. Megan, Inc., 222 F.3d 1347, 1352-53 (Fed. Cir. 2000) (holding that
renaming or re-identifying items in the disclosure to comport with later-developed and
more precise nomenclature is not new matter). There is no specific deadline by which
such a clarifying amendment must be made.

Background on incorporation by reference:

Whether and to what extent a patent incorporates material by reference is a
question of law reviewed de novo. Cook Biotech Inc. v. Acell, Inc., 460 F.3d 1365, 1376
(Fed. Cir. 2006).

Within the case:

Harari argues that the ’880 application filing makes
clear to any reader that the “same day as the present application” is the day on which
the parent application was filed. He argues that the inventor’s declaration need not
refer to the preliminary amendment in order for the examiner to enter the amendment
because the preliminary amendment does not contain any new matter compared to the
initial parent application. 37 C.F.R. § 1.63(d)(1)(iii).