  United States Court of Appeals
      for the Federal Circuit
                ______________________

                  ARCTIC CAT INC.,
                     Appellant

                           v.

           GEP POWER PRODUCTS, INC.,
                      Appellee
               ______________________

                 2018-1520, 2018-1521
                ______________________

    Appeals from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in Nos. IPR2016-
01385, IPR2016-01388.
                 ______________________

                Decided: March 26, 2019
                ______________________

   JASON STEWART JACKSON, Kutak Rock LLP, Omaha,
NE, argued for appellant. Also represented by NIALL
ANDREW MACLEOD, Minneapolis, MN.

    MICHAEL T. GRIGGS, Boyle Fredrickson, S.C., Milwau-
kee, WI, argued for appellee. Also represented by ERIC J.
LALOR, SARAH M. WONG.
                 ______________________

 Before PROST, Chief Judge, REYNA and TARANTO, Circuit
                        Judges.
2                ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.




TARANTO, Circuit Judge.
    Arctic Cat Inc. owns U.S. Patent Nos. 7,072,188 and
7,420,822, which are both titled “Power Distribution Mod-
ule for Personal Recreational Vehicle.” The patents de-
scribe an assertedly inventive electrical-connection box
having an array of receptacle openings that allow wires to
be arranged and secured in various positions for distrib-
uting power to various electrical components, including
components of a personal recreational vehicle. GEP Power
Products, Inc. petitioned the Patent Trial and Appeal
Board for inter partes reviews of all claims of both patents.
The Board determined that all claims of the ’188 and ’822
patents are unpatentable.
     Arctic Cat appeals. It argues principally that the
Board erred by (1) rejecting Arctic Cat’s submission of the
full transcript of its inventor’s deposition, (2) construing
various claim preambles as not stating limitations on the
claimed inventions, and (3) finding U.S. Patent No.
6,850,421 (Boyd) to be prior art applicable against the ’188
and ’822 patents. We conclude that the Board did not
abuse its discretion in rejecting the deposition-transcript
submission; that the Board correctly held preamble refer-
ences to a vehicle in the claims at issue not to be limiting;
but that the Board improperly determined that Boyd was
prior art. Based on those conclusions, as to the ’188 patent,
we reverse in part, vacate in part, and remand for further
proceedings. As to the ’822 patent, we affirm.
                              I
                             A
     The ’822 patent issued from an application that was a
continuation of the application from which the ’188 patent
issued. The patents claim the same priority date of October
29, 2002, when the application for the ’188 patent was filed,
and they have essentially the same specification. The spec-
ification describes a power distribution module, which
ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.                     3



includes a housing and a cover. ’188 patent, col. 1, lines
61–64; ’822 patent, col. 2, lines 5–7. The interior of the
housing includes a “component attachment portion,” which
is a wall with an array of electric-receptacle openings
meant for “receiving and securing electrical components.”
’188 patent, col. 1, line 61 through col. 2, line 1; ’822 patent,
col. 2, lines 8–11. The module also includes a distribution
harness with electrical conductors that connect electrical
components to the receptacles and facilitate power distri-
bution. ’188 patent, col. 2, lines 1–6; ’822 patent, col. 2,
lines 12–16. The specification states that “[a]nother aspect
of the present invention is directed to a personal recrea-
tional vehicle having an electrical distribution system” that
includes the same power distribution module. ’188 patent,
col. 2, lines 7–9; ’822 patent, col. 2, lines 17–19. The inven-
tion is purportedly useful because standardization of com-
ponents across different vehicle models reduces
manufacturing time and costs. See ’188 patent, col. 1, lines
38–55; ’822 patent, col. 1, lines 50–67.
    In the ’188 patent, claims 1, 11, and 19 are independ-
ent. Claim 1 reads:
       1. A power distribution module for a personal
    recreational vehicle comprising:
        a housing defining an interior, including a com-
    ponent attachment portion and a cover, the cover
    comprising a first surface substantially surround-
    ing the perimeter thereof, the first surface conform-
    ing to a first edge surrounding the perimeter of the
    component attachment portion, the component at-
    tachment portion comprising a fastener secured
    thereto proximate the first edge thereof, the fas-
    tener selectively securing the component attach-
    ment portion to the cover having the first surface
    of the cover in engagement with the first edge of
    the component attachment portion, the housing
    further including a plurality of receptacle openings
4                ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.




    in a wall in the component attachment portion,
    wherein the receptacle openings are spaced-apart
    in rows and columns of openings, the spacing be-
    tween the rows and the spacing between the col-
    umns being substantially the same for receiving
    and securing at least one electrical component
    within the housing across multiple rows or across
    multiple columns of openings; and
        a distribution harness having a plurality of elec-
    trical conductors, wherein the electrical conductors
    electrically cooperate with the receptacle openings
    to connect to the at least one electrical component,
    wherein the conductors are adapted to distribute
    power.
’188 patent, col. 7, lines 5–30. The preamble of claim 11 is
the same as the preamble of claim 1: “[a] power distribution
module for a personal recreational vehicle.” Compare id.,
col. 7, lines 5–6, with id., col. 7, lines 60–61. The preamble
of claim 19 recites only a “power distribution module.” Id.,
col. 8, line 53.
    In the ’822 patent, claims 1, 5, and 10 are independent.
Claim 1 reads:
       1. A personal recreational vehicle comprising:
       an electrical distribution system for distrib-
    uting electrical signals and power, the electrical
    distribution system including a power distribution
    module, wherein at least a portion of the electrical
    signals and power passes through the power distri-
    bution module, the power distribution module in-
    cluding:
       a housing having a plurality of receptacle open-
    ings in a substantially flat wall, the wall having a
    front side and a back side, wherein the receptacle
    openings are positioned in an array of at least three
    equally spaced-apart rows and at least three
ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.                   5



    equally spaced-apart columns, the receptacle open-
    ings positioned to receive electrical components on
    the front side of the wall across any adjacent open-
    ings in at least one row of the array; and
        a distribution harness on the backside of the
    wall opposite the receptacle openings, the distribu-
    tion harness having a plurality of electrical conduc-
    tor cables, wherein the electrical conductor cables
    electrically cooperate with the receptacle openings
    for receiving electrical components.
’822 patent, col. 7, lines 7–27. Claim 5’s preamble recites
an “electrical distribution module for a vehicle,” id., col. 7,
line 41, and claim 10’s preamble recites a “power distribu-
tion module,” id., col. 8, line 29. We do not set out those
claims in full, as any differences from claim 1 are not ma-
terial to the issues we decide.
                              B
    In July 2016, GEP filed petitions for inter partes re-
views of the ’188 and ’822 patents under 35 U.S.C. §§ 311–
19, challenging all claims as unpatentable for anticipation
or obviousness under 35 U.S.C. §§ 102 and 103. 1 For the
’188 patent, the Board instituted a review on three
grounds: (1) anticipation of claims 1–6, 11, 19, 22, and 23
by Boyd; (2) obviousness of claims 12–18 over Boyd, U.S.
Patent No. 5,354,211 (Svette), and U.S. Patent No.
3,660,869 (Caveney); and (3) obviousness of claims 1–12
and 19–23 over Svette alone. For the ’822 patent, the
Board also instituted a review on three grounds: (1) antici-
pation of claims 1, 2, 5, 9, and 10 by Boyd; (2) obviousness
of claims 3, 4, and 6–8 over Boyd and Svette; and (3)


    1   As the parties agree, this case is governed by the
Title 35 provisions in effect before the changes made by the
Leahy-Smith America Invents Act (AIA), Pub. L. No. 112-
29, 125 Stat. 284 (2011), took effect.
6                ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.




obviousness of claims 1–10 over Svette and U.S. Patent No.
6,121,548 (Matsuoka).
    After the Board instituted its reviews, Arctic Cat filed
its Patent Owner Responses on April 3, 2017. In its re-
sponses, Arctic Cat relied on statements in a declaration by
Mr. Darrel Janisch, an Arctic Cat employee and the sole
inventor listed on the ’188 and ’822 patents. GEP cross-
examined Mr. Janisch in a deposition on May 25, 2017.
GEP filed its replies in the two proceedings on June 30,
2017, citing statements that Mr. Janisch made during his
deposition. Rather than filing the full deposition transcript
with its replies, GEP submitted only the portions it cited.
Nearly three months later, on September 20, 2017, Arctic
Cat submitted the full deposition transcript to the Board,
without any request for permission. In orders dated the
same day, the Board expunged that submission from the
record. Citing 37 C.F.R. § 42.7(a), which permits the Board
to expunge papers that are “not authorized,” the Board de-
termined that Arctic Cat’s submission was “unauthorized
and untimely.” J.A. 81. More specifically, it noted that
Arctic Cat “did not seek authorization” to file the tran-
script, nor did Arctic Cat “explain[] why . . . the transcript
could not have been filed earlier (for example, by the due
date in the Scheduling Order for Motions for Observation).”
Id.
    The Board issued its final written decisions on Decem-
ber 5, 2017. GEP Power Prods., Inc. v. Arctic Cat Inc., No.
IPR2016-01385 (P.T.A.B. Dec. 5, 2017), Paper No. 27 (’188
Board Decision); GEP Power Prods., Inc. v. Arctic Cat Inc.,
No. IPR2016-01388 (P.T.A.B. Dec. 5, 2017), Paper No. 31
(’822 Board Decision).
    As an initial matter, the Board rejected part of Arctic
Cat’s argument that certain language in the claim pream-
bles is limiting, i.e., defines the inventions to be assessed
for patentability. Specifically, the Board concluded that
the asserted claims in the ’188 patent are not limited by
ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.                7



preamble language referring to a personal recreational ve-
hicle and that the same is true of claims 1–4 of the ’822
patent. ’188 Board Decision at 9–12; ’822 Board Decision
at 9–12. With respect to those claims, the Board reasoned
that “the claim bodies . . . describe structurally complete
inventions” that do not include personal recreational vehi-
cles and that the preambles “recite[] only an intended use
for the otherwise complete claimed apparatus.” ’188 Board
Decision at 11; see ’822 Board Decision at 9–12. The Board
did not decide the limiting effect of preamble language in
claims 5–10 of the ’822 patent, deeming such a decision un-
necessary because, for those claims, Arctic Cat did not rely
on the preambles in opposing GEP’s unpatentability chal-
lenge, at least with respect to the ground relying on Svette
and Matsuoka. ’822 Board Decision at 10. 2
    Next, the Board addressed the prior-art status of Boyd,
whose filing date of April 1, 2002, is about seven months
before the October 2002 filing date of the ’188 patent (to
which the ’822 patent claims priority). The Board con-
cluded that Boyd is prior art to those patents under 35
U.S.C. § 102(e). The Board rejected Arctic Cat’s two argu-
ments to the contrary.
    First, the Board rejected Arctic Cat’s arguments that
the ’188 and ’822 patents were entitled to a priority date
before April 1, 2002, because Mr. Janisch conceived the in-
ventions at issue before that date and diligently worked to


    2    In this court, Arctic Cat does not contend that the
Board erred in not deciding the preamble issue for claims
5–10 of the ’822 patent. Moreover, when challenging the
Board’s determination of unpatentability of all the ’822 pa-
tent’s claims based on Svette and Matsuoka, Arctic Cat re-
lies on the preambles only for claims 1–4, not for the other
challenged claims of the ’822 patent. Br. for Appellant at
41, 51. For the ’822 patent, therefore, we decide the limit-
ing effect of the preambles only for claims 1–4.
8                ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.




reduce them to practice. ’188 Board Decision at 15–22; ’822
Board Decision at 14–22. The Board relied entirely on the
diligence requirement in rejecting Arctic Cat’s argument
for antedating Boyd; it did not question Mr. Janisch’s con-
ception before April 2002. 3 Arctic Cat offered a declaration
from Mr. Janisch, including a timeline of important emails
during the relevant months. But the Board determined
that Mr. Janisch’s timeline lacked a “sufficiently detailed
explanation of events occurring between the bookend com-
munications.” ’188 Board Decision at 18; ’822 Board Deci-
sion at 17–18.
     Second, the Board rejected Arctic Cat’s additional ar-
guments against use of Boyd as prior art—namely, that the
relevant, allegedly anticipatory portions of Boyd are not ac-
tually “by another,” as required by 35 U.S.C. § 102(e), even
though the only named inventor on Boyd is Mr. Boyd him-
self, not Mr. Janisch. ’188 Board Decision at 22–27; ’822
Board Decision at 22–27. The Board noted that a lack of
“overlap in inventive entities” does not necessarily mean
that an earlier reference is “by another,” citing In re
Mathews, 408 F.2d 1393 (C.C.P.A. 1969). But the Board
determined that, on the evidence presented, it could not
find that the relevant portions of Boyd were derived from
the work of Mr. Janisch—whose employer, Arctic Cat, had
hired Mr. Boyd’s employer to reduce Mr. Janisch’s concep-
tion to practice. ’188 Board Decision at 23–25; ’822 Board
Decision at 23–25. Given its conclusions that Boyd is “by
another” and that Arctic Cat did not successfully antedate
Boyd, the Board determined that Boyd is prior art against
the ’188 and ’822 patents. ’188 Board Decision at 27; ’822
Board Decision at 27.




    3   GEP has not sought a remand on the conception is-
sue if we disagree with the Board on diligence. We there-
fore take conception before April 2002 as settled.
ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.                 9



    Ultimately, the Board held all claims of the ’188 and
’822 patents unpatentable on all instituted grounds, rely-
ing on Boyd at least in part with respect to most, though
not all, of the claims and grounds. ’188 Board Decision at
39; ’822 Board Decision at 38. Arctic Cat timely appealed
the Board’s decisions. We have jurisdiction under 28
U.S.C. § 1295(a)(4)(A).
                             II
    Arctic Cat first challenges the Board’s decision to ex-
punge from the record the full transcript of Mr. Janisch’s
deposition that Arctic Cat submitted. We review such an
evidentiary decision for an abuse of discretion. See Belden
Inc. v. Berk-Tek LLC, 805 F.3d 1064, 1077–78 (Fed. Cir.
2015); Chen v. Bouchard, 347 F.3d 1299, 1307 (Fed. Cir.
2003). Although we do not reject Arctic Cat’s main argu-
ment about the full transcript, we find no abuse by the
Board in this case.
     Arctic Cat’s main point relies on a regulation that ad-
dresses numerous aspects of the taking and use of deposi-
tion testimony, namely, 37 C.F.R. § 42.53. The regulation
declares that such testimony must be submitted “in the
form of a deposition transcript,” § 42.53(a), and in subsec-
tion (f) specifies certain procedures, “[w]hen the testimony
has been transcribed,” for dealing with the “transcript of
the deposition,” § 42.53(f)(5). Paragraph (7) of subsection
(f) declares:
    Except where the parties agree otherwise, the pro-
    ponent of the testimony must arrange for providing
    a copy of the transcript to all other parties. The
    testimony must be filed as an exhibit.
§ 42.53(f)(7) (emphasis added).
    Arctic Cat contends that the best reading of the quoted
regulatory language is that, when a party submits some
testimony from a deposition, that party (the proponent)
must submit the transcript of the entire deposition, or that,
10               ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.




in any event, the adversary party may submit the entire
transcript if the proponent of the testimony does not. At
least one Board panel in another inter partes review con-
cluded that the proponent of any deposition testimony is
indeed obliged to file the full transcript. See Zhongshan
Broad Ocean Motor Co. v. Nidec Motor Corp., No. IPR2014-
01121 (P.T.A.B. Sept. 10, 2015), Paper No. 42, at 2. 4 If Arc-
tic Cat’s reading of the regulation is right, the regulation
may well provide the authorization that the Board found
missing when it invoked its discretion under 37 C.F.R.
§ 42.7(a) to expunge material “that is not authorized.”
     But we need not decide whether Arctic Cat’s reading is
correct. Even if the regulation provides for submission of a
full transcript in the way Arctic Cat argues, the regulation
does not say that the submission at issue here—made by
Arctic Cat after GEP submitted excerpts as a proponent of
deposition testimony given by Mr. Janisch—may be made
at any time. Arctic Cat sensibly agrees that the Board has
discretion to decide when a filing is too late. Oral Arg. at
10:21–38,      http://oralargu   ments.cafc.uscourts.gov/de-
fault.aspx?fl=2016-1374.mp3. The Board concluded that
Arctic Cat did not “explain[] why . . . the transcript could
not have been filed earlier (for example, by the due date in
the Scheduling Order for Motions for Observation).” J.A.
81. Given the strong statute-based interest in expedition
in inter partes reviews, we see no basis for deeming the
Board’s expungement decision in this case to be an abuse
of discretion.



     4   Until May 2015, the second sentence of § 42.53(f)(7)
stated that the testimony “must be filed by the proponent”
of the testimony. The Director deleted “by the proponent”
in order “[t]o clarify that either party is permitted to file
testimony as an exhibit.” 80 Fed. Reg. 28,561, 28,563 (May
19, 2015). The Board rendered its decision in Zhongshan
after that change took effect.
ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.                  11



                              III
    Arctic Cat next challenges the Board’s determination
that certain preamble language in certain claims of the
’188 and ’822 patents is not limiting. Before the Board, the
only aspect of the preamble language that Arctic Cat mean-
ingfully argued to be limiting is language referring to a
“personal recreational vehicle”; Arctic Cat did not argue
that the label “power distribution module” in the pream-
bles is limiting. The Board therefore confined its preamble
analysis to the contention about the “personal recreational
vehicle” language. So do we.
    We look to case law from our court and its predecessor.
The effect of preamble language is not addressed in the
statute, which does not mention preambles. Only one reg-
ulation promulgated by the Patent and Trademark Office
addresses preambles, 37 C.F.R. § 1.75(e); as discussed in-
fra, that regulation is of relevance here. Supreme Court
cases that mention “preambles” in patent claims are few
and do not provide general guidance on their effect. See
Consolidated Rolling Mill Co. v. Barnard & Leas Mfg. Co.,
156 U.S. 261, 268 (1895) (noting that applicant amended
preamble during prosecution); Burr v. Duryee, 68 U.S. (1
Wall.) 531 (1863).
    As an overarching idea, we have said that “[i]n general,
a preamble limits the invention if it recites essential struc-
ture or steps, or if it is ‘necessary to give life, meaning, and
vitality’ to the claim.” Catalina Mktg. Int’l, Inc. v. Coolsav-
ings.com, Inc., 289 F.3d 801, 808 (Fed. Cir. 2002) (quoting
Pitney Bowes, Inc. v. Hewlett-Packard Co., 182 F.3d 1298,
1305 (Fed. Cir. 1999)). We also have said that “[w]hether
to treat a preamble as a limitation is ‘determined on the
facts of each case in light of the overall form of the claim,
and the invention as described in the specification and il-
luminated in the prosecution history.’” Deere & Co. v. Bush
Hog, LLC, 703 F.3d 1349, 1357 (Fed. Cir. 2012) (quoting
Applied Materials, Inc. v. Advanced Semiconductor
12               ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.




Materials America, Inc., 98 F.3d 1563, 1572–73 (Fed. Cir.
1996)). And “[t]his court has recognized that as a general
rule preamble language is not treated as limiting.” Aspex
Eyewear, Inc. v. Marchon Eyewear, Inc., 672 F.3d 1335,
1347 (Fed. Cir. 2012) (citing Allen Eng’g Corp. v. Bartell
Indus., Inc., 299 F.3d 1336, 1346 (Fed. Cir. 2002)).
    Those general formulations have for decades been im-
plemented through a number of more concrete and objec-
tive rules. Catalina, 289 F.3d at 808−09; see Summit 6,
LLC v. Samsung Electronics Co., 802 F.3d 1283, 1292 (Fed.
Cir. 2015); Deere, 703 F.3d at 1358; Rowe v. Dror, 112 F.3d
473, 478 (Fed. Cir. 1997). Those rules have a long history,
and have thus shaped drafting practices, so they play a role
akin to that of canons of construction in statutory interpre-
tation. They channel the work of identifying the “under-
standing of what the inventors actually invented and
intended to encompass by the claim.” Corning Glass Works
v. Sumitomo Elec. U.S.A., Inc., 868 F.2d 1251, 1257 (Fed.
Cir. 1989).
    We have treated the effect of preamble language as a
claim-construction issue. See Deere, 703 F.3d at 1357. We
decide claim construction de novo as an issue of law where,
as here, the issue is decided only on the intrinsic evidence.
Teva Pharm. USA, Inc. v. Sandoz, Inc., 135 S. Ct. 831, 837–
38, 841 (2015); Hamilton Beach Brands, Inc. v. f’real Foods,
LLC, 908 F.3d 1328, 1339 (Fed. Cir. 2018). In this case, it
makes no difference to our conclusion whether the stand-
ard from Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir.
2005) (en banc), or a “broadest reasonable interpretation”
standard applies to this threshold issue of claim construc-
tion.
                             A
    The preambles in claims 1 and 11 of the ’188 patent
recite “[a] power distribution module for a personal recrea-
tional vehicle.” The Board determined that those pream-
bles are not limiting because the bodies of claims 1 and 11
ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.               13



“describe structurally complete inventions” and the pream-
bles refer to a personal recreational vehicle only as an in-
tended use. ’188 Board Decision at 11. We agree.
    We have long ruled that “a preamble is not limiting
‘where a patentee defines a structurally complete invention
in the claim body and uses the preamble only to state a
purpose or intended use for the invention.’” Catalina, 289
F.3d at 808 (quoting Rowe, 112 F.3d at 478); see
Georgetown Rail Equip. Co. v. Holland L.P., 867 F.3d 1229,
1236−37 (Fed. Cir. 2017); Deere, 703 F.3d at 1358. That
rule is grounded in the statutory distinction, in identifying
the permissible subject matter of a patent claim, between
a physical product (which may be defined in part by its
claimed functional capabilities) and activities that consti-
tute a process (which may include a new “use” of a known
invention). See 35 U.S.C. § 101 (“process” versus “machine,
manufacture, or composition of matter”); 35 U.S.C. § 100(b)
(defining “process”); MasterMine Software, Inc. v. Microsoft
Corp., 874 F.3d 1307, 1312−16 (Fed. Cir. 2017) (explaining
impermissibility of mixing products with processes in
claims). In particular, the rule against giving invention-
defining effect to intended-use preamble language reflects
a longstanding substantive aspect of the patent statute—
specifically, the “well settled” fundamental principle “that
the recitation of a new intended use for an old product does
not make a claim to that old product patentable.” In re
Schreiber, 128 F.3d 1473, 1477 (Fed. Cir. 1997); see In re
Zierden, 411 F.2d 1325, 1328−29 (C.C.P.A. 1969); In re
Sinex, 309 F.2d 488, 492 (C.C.P.A. 1962); Kropa v. Robie,
187 F.2d 150, 152 (C.C.P.A. 1951); see also Catalina, 289
F.3d at 809 (discussing Roberts v. Ryer, 91 U.S. 150, 157
(1875), and In re Gardiner, 171 F.2d 313, 315−16 (C.C.P.A.
1948))
    In its discussion of claims 1 and 11, the Board correctly
noted the following:
14                ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.




     [T]hose claims recite limitations including . . . a
     housing with a component attachment portion and
     a cover, a plurality of receptacles in the component
     attachment portion, and a distribution harness
     having a plurality of electrical conductors that elec-
     trically cooperate with the receptacles to connect to
     at least one electrical component. The bodies of
     those claims do not recite a personal recreational
     vehicle.
’188 Board Decision at 11. Moreover, in the preambles, the
reference to a “personal recreational vehicle” merely iden-
tifies an intended use for the claimed power distribution
module. This preamble language does not claim the vehi-
cle; it claims only the module (the name for what is defined
in the bodies of the claims) and identifies a use for that
module—in a personal recreational vehicle. Arctic Cat has
not demonstrated that the identified use itself imposes any
structural requirement on the claimed module beyond
what is required by the bodies of the claims. Nor has it
shown any “reliance on the preamble during prosecution to
distinguish the claimed invention from the prior art.” Cat-
alina, 289 F.3d at 808.
    For these preambles, therefore, the result is controlled
by the principle that “a preamble is not limiting ‘where a
patentee defines a structurally complete invention in the
claim body and uses the preamble only to state a purpose
or intended use for the invention.’” Id. (quoting Rowe, 112
F.3d at 478). As in Catalina, “deletion of the disputed
phrase from the preamble . . . [would] not affect the struc-
tural definition or operation of the [invention] itself.” Id.
at 810. We hold that the preambles in claims 1 and 11 of
the ’188 patent do not limit claims 1–18 in that patent.
                               B
    For the ’822 patent, as we have noted, a preamble issue
is presented only by claim 1 (and dependent claims 2–4).
The preamble of claim 1 recites “[a] personal recreational
ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.                 15



vehicle.” The Board determined that this preamble is non-
limiting, essentially for the same reasons as for claims 1
and 11 of the ’188 patent. Compare ’822 Board Decision at
9–12, with ’188 Board Decision at 9–12. We agree.
    This claim language does recite “additional structure”
(the personal recreational vehicle) over and above the
structure recited in the body of the claims (the power dis-
tribution module). But not every preamble reference to ad-
ditional structure is limiting, even when the structure is
noted in the specification—even, indeed, when the struc-
ture is “underscored as important by the specification.” See
Catalina, 289 F.3d at 808 (“[W]hen reciting additional
structure or steps underscored as important by the specifi-
cation, the preamble may operate as a claim limitation.”
(emphasis added)). For the claims at issue here, we con-
clude, the reference to the personal recreational vehicle
does not suffice to be part of the definition of the invention,
understood in light of the specification.
     The rules we have articulated about what preamble
language reciting structure is limiting are telling about
what is missing here. The vehicle language here does not
supply “antecedent basis” for terms in the body defining a
module; nor does it supply structure needed to make the
body itself a “structurally complete invention.” Id. Rather,
it merely adds structure of which the body-recited module
is a part. 5 And Arctic Cat does not argue that the preamble
language at issue was relied on during prosecution to dis-
tinguish prior art so as to make it part of the invention as




    5   Claim 5 of the ’822 patent refers in the body to “the
conductor cables extending from the housing to route
power signals throughout the vehicle.” We do not address
that reference to “the vehicle,” because we do not have a
preamble issue as to claim 5 before us.
16               ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.




understood upon issuance. See id. (noting rule giving lim-
iting effect to such preamble language).
     Moreover, the structure recited in the preamble is iden-
tified only as a “personal recreational vehicle,” and what
the specification says about it is distinctly limited. The
Summary of the Invention in the specification, after stating
that “[o]ne aspect of the present invention” is the module,
’188 patent, col. 1, lines 60–61; ’822 patent, col. 2, lines 3–
5, does go on to state that “[a]nother aspect of the present
invention is directed to a personal recreational vehicle”
having claimed features regarding electrical distribution,
’188 patent, col. 2, lines 7–8; ’822 patent, col. 2, lines 17–
18. And Figure 1 shows a vehicle, not just the module. But
the “aspect” statement is conclusory, and the figure is skel-
etal. What is missing in the specification is any identifica-
tion of a feature of the vehicle that is asserted to be an
improvement other than the “power distribution module”
as described in the various claims. The vehicle in the pre-
amble is entirely conventional apart from the improvement
in the body of the claims. In this respect, the preamble here
differs crucially from those in cases such as Proveris Scien-
tific Corp. v. Innovasystems, Inc., 739 F.3d 1367, 1373 (Fed.
Cir. 2014); Deere, 703 F.3d at 1358; and Poly-Am., L.P. v.
GSE Lining Tech., Inc., 383 F.3d 1303, 1310 (Fed. Cir.
2004).
    The relation between the preamble and body here
makes the claim language here almost fit—but not actually
fit—a pattern addressed in longstanding case law about
claims in Jepson form. We have long held that preamble
language is limiting when the claim recites a combination
in the way specified in the one PTO regulation on pream-
bles, i.e., by describing the “conventional or known” ele-
ments in a “preamble,” followed by a transition phrase
“such as ‘wherein the improvement comprises,’” and then
an identification of elements that “the applicant considers
as the new or improved portion.” 37 C.F.R. § 1.75(e) (based
on Ex parte Jepson, 243 Off. Gaz. Pat. Office 525 (Ass’t
ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.                17



Comm’r Pat. 1917)); see Catalina, 289 F.3d at 808; Rowe,
112 F.3d at 479 (“When this form is employed, the claim
preamble defines not only the context of the claimed inven-
tion, but also its scope.”); Pentec, Inc. v. Graphic Controls
Corp., 776 F.2d 309, 315 (Fed. Cir. 1985) (same). But the
claim language chosen by Arctic Cat crucially differs from
Jepson language and so does not fall under the case law for
Jepson language: it does not use the required transitional
phrase. Where an applicant chose not to use the well-es-
tablished Jepson transitional phrase, and the preamble is
wholly conventional while only the body of the claim iden-
tifies an improvement, that choice is a powerful reason to
deny the preamble the limiting effect it would have had if
the “improvement” transitional phrase had been used.
     For those reasons, we hold that the preamble of claim
1 of the ’822 patent does not limit claims 1–4 of that patent.
                             IV
    Arctic Cat argues that the Board incorrectly ruled that
Boyd, having a filing date (and hence relevant priority
date) of April 1, 2002, is prior art for purposes of the two
patents at issue here, which on their faces claim priority
only to October 29, 2002. We agree with Arctic Cat.
    It is undisputed that, for Boyd to be prior art, it must
come within 35 U.S.C. § 102(e)(2), which declares that an
inventor is not entitled to a patent on an invention if “the
invention was described in . . . a patent granted on an ap-
plication for patent by another filed in the United States
before the invention by the applicant for patent,” subject to
an exception not relevant in this case. Arctic Cat argued
to the Board that, even though Boyd’s application was filed
before the application for the ’188 patent (and the later ap-
plication for the ’822 patent), § 102(e)(2) does not apply to
Boyd for two reasons. First, Arctic Cat argued that Mr.
Janisch invented the subject matter of the claims at issue
before April 1, 2002, so that the Boyd application came af-
ter, not “before,” the “invention by the applicant” (Mr.
18               ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.




Janisch). Second, Arctic Cat argued that the disclosures in
Boyd relevant to the patentability of the claims at issue are
not actually “by another” (i.e., someone different from Mr.
Janisch), because those disclosures set forth inventions of
Mr. Janisch, not Mr. Boyd. Either one of those arguments,
if accepted, would eliminate Boyd as prior art in this mat-
ter. The Board rejected both.
    Arctic Cat challenges the Board’s conclusions on both
the antedating and “by another” issues. We agree with Arc-
tic Cat that the Board erred in its rejection of Arctic Cat’s
proof that Mr. Janisch’s inventions antedate April 1, 2002.
We therefore do not reach the “by another” issue.
    Antedating of Boyd in this case required that Mr. Jan-
isch have (1) conceived of the inventions at issue before
April 1, 2002, and (2) diligently reduced the conceptions to
practice. See Perfect Surgical Techniques, Inc. v. Olympus
America, Inc., 841 F.3d 1004, 1007 (Fed. Cir. 2016). The
parties treat the inventions of the claims at issue as a sin-
gle invention for these purposes. In addition, they do not
dispute that Mr. Janisch’s conception pre-dated April 1,
2002, or that he was diligent up to April 1, 2002. The only
issue, therefore, is Mr. Janisch’s diligence in reducing the
invention to practice from April 1, 2002, until the reduction
to practice was completed on October 29, 2002, with the fil-
ing of the application that issued as the ’188 patent.
    “Reasonable diligence must be shown throughout the
entire critical period, which begins just prior to the compet-
ing reference’s effective date and ends on the date of the
invention’s reduction to practice.” Id. An inventor’s testi-
mony of reasonable diligence throughout the critical period
“must be corroborated by evidence.” Id. We apply a “rule
of reason” to evaluate such corroborating evidence. Id. at
1008.
    Crucially for this case, diligence need not be perfectly
continuous—only reasonably continuous. Id. at 1009.
“[P]eriods of inactivity within the critical period do not
ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.               19



automatically vanquish a patent owner’s claim of reasona-
ble diligence.” Id. “[T]he point of the diligence analysis is
not to scour the patent owner’s corroborating evidence in
search of intervals of time where the patent owner has
failed to substantiate some sort of activity.” Id. Rather,
the adequacy of the reduction to practice is determined by
whether, “in light of the evidence as a whole, ‘the invention
was not abandoned or unreasonably delayed.’” Id. (quoting
Brown v. Barbacid, 436 F.3d 1376, 1379 (Fed. Cir. 2006)).
“Whether a patent antedates a reference is a question of
law based on subsidiary findings of fact,” and “[t]he issue
of reasonable diligence ‘turns on the factual record, and we
review Board determinations as to diligence for support by
substantial evidence in the record.’” Id. at 1008 (quoting
In re Steed, 802 F.3d 1311, 1317 (Fed. Cir. 2015)).
    We conclude that the records in the two proceedings
before us (which are materially identical) establish that
Mr. Janisch was reasonably diligent during the critical pe-
riod so as not to have abandoned his invention or unrea-
sonably delayed its reduction to practice. The Board
concluded that the evidence did not establish diligence
throughout the period from April 1, 2002, to October 29,
2002. ’188 Board Decision at 22. 6 But the Board’s analysis
rested on too rigid a standard, and the record establishes
diligence under the correct standard.
    Mr. Janisch submitted a declaration that included a
2002 timeline with citations to exhibits to demonstrate his
efforts to reduce his invention to practice. J.A. 1584–86.
The Board took issue with some of the date ranges in that
timeline, particularly from April 1 to April 29 and from Au-
gust 16 to October 18. ’188 Board Decision at 18–19. Alt-
hough the Board said that it was not “scour[ing] the record
for gaps in activity,” it criticized Mr. Janisch for not


    6  We cite only the ’188 Board Decision. The ’822
Board Decision is materially identical on the issue.
20               ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.




“account[ing] for” approximately half of the days during the
critical period. Id. at 19–20. It also faulted Mr. Janisch for
providing “conclusory explanations, which lack specifics as
to facts and dates.” Id. at 21.
    But in the context of this case, the details the Board
found missing from Mr. Janisch’s explanation do not sug-
gest lack of reasonable diligence. During the identified
gaps in Mr. Janisch’s personal activity, the invention was
being tested at Mr. Boyd’s employer, Tyco, hired by Arctic
Cat for that purpose. See id. at 20. Lack of diligence cannot
be inferred from putting the invention into someone else’s
hands for needed testing and awaiting test results for a
short period commensurate with the testing need, at least
where oversight was diligent. That course of action, as a
way of reducing an invention to practice, does not give rise
to an inference of unreasonable delay or abandonment of
the invention. See Perfect Surgical, 841 F.3d at 1009
(“That an inventor overseeing a study did not record its
progress on a daily, weekly, or even monthly basis does not
mean the inventor necessarily abandoned his invention or
unreasonably delayed it.” (emphasis added)).
    Here, the evidence confirms Mr. Janisch’s diligent
oversight—indeed, his persistence in moving the project of
reduction to practice through multiple stages in a timely
manner. The product specifications and test protocols went
through five revisions in only five months. Compare J.A.
1621 (revision 3 on March 15, 2002), with J.A. 1632 (revi-
sion 8 on August 16, 2002). Mr. Janisch pressed for pro-
gress. In an internal email dated May 17, 2002, Mr.
Janisch asked with apparent urgency about getting sup-
plies needed for testing: “How soon can we expect to receive
the . . . decals?” J.A. 1625 (emphasis added). In another
email, dated August 16, 2002, Mr. Janisch directed Tyco:
“Please keep us appraised of Tyco test results, as they are
completed.” J.A. 1632 (emphasis added). There is no sub-
stantial evidence of any meaningful inattention to the task
of reducing the invention to practice. Reviewing all the
ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.                21



evidence under a rule of reason, we conclude that the only
possible result on this record is that Mr. Janisch was rea-
sonably diligent in reducing his invention to practice.
     There being no dispute about conception before April
2002, we hold that Mr. Janisch’s invention antedated Boyd.
It follows that Boyd is not available as prior art against the
’188 and ’822 patents. In light of that holding, we do not
reach the issue of whether Boyd is “by another” under
§ 102(e).
                              V
    Our resolution of the above issues has the following
consequences for the Board’s unpatentability rulings.
    For the ’188 patent, the Board determined that claims
1–6, 11, 19, 22, and 23 are unpatentable as anticipated by
Boyd. The Board also determined that claims 12–18 are
unpatentable for obviousness over Boyd, Svette, and
Caveney. Those two instituted grounds, as presented by
GEP to the Board, depend on Boyd being prior art. Because
we hold that Boyd is not prior art, we reverse the Board’s
unpatentability rulings on the first and second instituted
grounds.
    The Board addressed a third instituted ground, ruling
that claims 1–12 and 19–23 are unpatentable for obvious-
ness over Svette alone. In so ruling, however, the Board
relied on Boyd as evidence of background knowledge that a
relevant artisan would have used to properly read Svette.
’188 Board Decision at 35 (citing Randall Mfg. v. Rea, 733
F.3d 1355, 1362 (Fed. Cir. 2013)). We hold that Boyd is not
prior art. We think it advisable to permit the Board to de-
termine in the first instance whether removal of Boyd from
the pool of prior art affects the proper outcome on the
Svette-only ground. We vacate the Board’s decision on the
third instituted ground and remand for further proceed-
ings, to be conducted without treating Boyd as prior art.
22                ARCTIC CAT INC. v. GEP POWER PRODUCTS, INC.




    For the ’822 patent, the Board determined, among
other things, that all the claims, namely, claims 1–10, are
unpatentable for obviousness over Svette and Matsuoka.
That ruling is not undermined by our holding that Boyd is
not prior art. Nor are we persuaded that the Board com-
mitted any other error undermining its unpatentability de-
termination as to those claims based on Svette and
Matsuoka. Contrary to Arctic Cat’s contentions, we do not
think that the Board shifted the burden of proving un-
patentability to Arctic Cat or that the Board erred in find-
ing what Matsuoka teaches. As to the ’822 patent, we
therefore affirm the Board’s decision.
                             VI
     We have considered the remaining arguments pre-
sented to us, but we find them unpersuasive. Accordingly,
the Board’s decision on the ’188 patent is reversed in part
and vacated in part, and the matter is remanded for further
proceedings consistent with this opinion. The Board’s de-
cision on the ’822 patent is affirmed.
      No costs.
     REVERSED IN PART, VACATED IN PART, AND
        REMANDED IN APPEAL NO. 2018-1520
         AFFIRMED IN APPEAL NO. 2018-1521
