United States Court of Appeals
      for the Federal Circuit
                ______________________

   IN RE: DAVID FOUGHT, MARTIN CLANTON,
                   Appellants
             ______________________

                      2019-1127
                ______________________

    Appeal from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in No. 13/507,528.
                  ______________________

              Decided: November 4, 2019
               ______________________

   RYAN MATTHEW FOUNTAIN, Mishawaka, IN, argued for
appellants.

   WILLIAM LAMARCA, Office of the Solicitor, United
States Patent and Trademark Office, Alexandria, VA, ar-
gued for appellee Andrei Iancu. Also represented by
THOMAS L. CASAGRANDE, THOMAS W. KRAUSE, JOSEPH
MATAL, COKE MORGAN STEWART.
                ______________________

   Before NEWMAN, MOORE, and CHEN, Circuit Judges.
MOORE, Circuit Judge.
    David Fought and Martin Clanton (collectively, Appel-
lants) are the named inventors on U.S. Patent Application
No. 13/507,528, filed on July 5, 2012. The examiner re-
jected claims 1 and 2 under 35 U.S.C. § 102(b), and the
2                                              IN RE: FOUGHT




Patent Trial and Appeal Board affirmed. Ex Parte Fought
& Clanton, No. 2017-000315, 

(P.T.A.B.
Aug. 28, 2018) (Board Decision). Because we hold the
Board erred in concluding “travel trailer” does not limit the
scope of the claims, we reverse and remand for further pro-
ceedings consistent with this opinion.
                       BACKGROUND
    The ’528 application relates to the construction of
travel trailers. The specification describes a preferred em-
bodiment of the trailer having two compartments, a living
quarters and a garage portion, separated by a wall assem-
bly. The application includes two claims:
    1. A travel trailer having a first and second com-
    partment therein separated by a wall assembly
    which is movable so as to alter the relative dimen-
    sions of the first and second compartments without
    altering the exterior appearance of the travel
    trailer.
    2. A travel trailer having a front wall, rear wall,
    and two side walls with a first and a second com-
    partment therein, those compartments being sepa-
    rated by a wall assembly, the wall assembly having
    a forward wall and at least one side member,
    the side member being located adjacent to and
    movable in parallel with respect to a side wall of
    the trailer, and
    the wall assembly being moved along the longitu-
    dinal length of the trailer by drive means posi-
    tioned between the side member and the side wall.
J.A. 17.
    The examiner rejected both claims under pre-AIA 35
U.S.C. § 102(b). The examiner rejected claim 1 as antici-
pated by U.S. Patent No. 4,049,311 (Dietrich), which de-
scribes a conventional truck trailer such as a refrigerated
IN RE: FOUGHT                                                3



trailer, and claim 2 as anticipated by U.S. Patent No.
2,752,864 (McDougal), which describes a bulkhead for ship-
ping compartments. Appellants responded to the rejec-
tions by arguing that a “travel trailer” is “a type of
recreational vehicle.” Appellants relied on U.S. Patent Ap-
plication Publication No. 2010/0096873 (Miller) as extrin-
sic evidence regarding the meaning of “travel trailer” and
“recreational vehicle.” 1 The examiner maintained his re-
jections. Appellants appealed to the Board and cited
Woodall’s RV Buyer’s Guide (Woodall’s) as additional evi-
dence to support their position. Appellants also argued to
the Board that the examiner erred by rejecting the claims
under § 102 without addressing the level of ordinary skill
in the art. The Board affirmed the examiner’s rejection,
concluding the preamble term “travel trailer” is a mere
statement of intended use that does not limit the claim. It
did not address Appellants’ argument that the examiner
was required to specify the level of ordinary skill in the art.
Appellants appeal. We have jurisdiction under 28 U.S.C.
§ 1295(a)(4)(A).
                         DISCUSSION
    We review the Board’s legal conclusions de novo and its
factual findings for substantial evidence. In re Gartside,

, 1313–15 (Fed. Cir. 2000).
                              I
    “We review the Board’s ultimate claim construction de
novo and its underlying factual determinations involving
extrinsic evidence for substantial evidence.” In re Man
Mach. Interface Techs. LLC, 

, 1285 (Fed. Cir.
2016).      Claims in pending applications receive


    1Appellants described Miller as also “deal[ing] with
movable walls within travel trailers” such that it “should
serve as a useful reference for the context of the present
invention.” J.A. 29.
4                                               IN RE: FOUGHT




their broadest reasonable interpretation during examina-
tion. In re Am. Acad. of Sci. Tech Ctr., 

, 1364
(Fed. Cir. 2004). We treat the effect of preamble language
as a claim construction issue. Arctic Cat Inc. v. GEP Power
Prod., Inc., 

, 1327 (Fed. Cir. 2019). “Pream-
ble language that merely states the purpose or intended
use of an invention is generally not treated as limiting the
scope of the claim.” Bicon, Inc. v. Straumann Co., 

, 952 (Fed. Cir. 2006). However, “the preamble consti-
tutes a limitation when the claim(s) depend on it for ante-
cedent basis.” C.W. Zumbiel Co., Inc. v. Kappos, 

, 1385 (Fed. Cir. 2012) (citing Catalina Mktg. Int’l, Inc.
v. Coolsavings.com, Inc., 

, 808 (Fed. Cir.
2002)).
    The parties dispute whether the preamble phrase
“travel trailer” limits the claims. Appellants begin by ar-
guing that the claims have no preamble at all. They argue
that “[a] travel trailer having . . .” is not a preamble and
does not use a transition word. Appellants’ Br. 23. We do
not agree. Though this claim does not use the typical claim
language (comprising) which denotes the transition be-
tween the preamble and the body, the word “having” per-
forms the same role here.
     Appellants next argue that even if “travel trailer” is
part of the preamble, it is limiting because limitations in
the body of the claims rely on “travel trailer” for antecedent
basis and for structural limitations. Appellants’ Br. 23–24.
The government argues that “travel trailer” does not struc-
turally limit the claims and the extrinsic evidence fails to
add specific structure. Appellee’s Br. 13–15. The Board
concluded that “travel trailer” is a non-limiting statement
of intended use. Board Decision at *3–4. We do not agree.
    In the body of claim 1, the limitation reciting “the
travel trailer” relies on the preamble’s recitation of “[a]
travel trailer” for its antecedent basis. We have repeatedly
held a preamble limiting when it serves as antecedent
IN RE: FOUGHT                                                 5



basis for a term appearing in the body of a claim. See, e.g.,
C.W. Zumbiel 

; Bell Commc’ns Re-
search, Inc. v. Vitalink Commc’ns Corp., 

, 620–
21 (Fed. Cir. 1995); Electro Sci. Indus., Inc. v. Dynamic De-
tails, Inc., 

, 1348 (Fed. Cir. 2002); Pacing
Techs., LLC v. Garmin Int’l, Inc., 

, 1024 (Fed.
Cir. 2015).
    To the extent that the Board determined that “travel
trailer” is simply a statement of intended use and not a
structural limitation, we do not agree. Appellants relied on
two pieces of extrinsic evidence, Miller and Woodall’s, to
support their assertion that “travel trailer” is a specific
type of recreational vehicle that includes a living quarters.
    The Board quoted relevant portions of the two refer-
ences:
    “Recreational vehicles” or “RVs,” as referred to
    herein, can be motorized or towed, but in general
    have a living area which provides shelter from the
    weather as well as personal conveniences for the
    user, such as bathroom(s), bedroom(s), kitchen,
    dining room, and/or family room. Each of these
    rooms typically forms a separate compartment
    within the vehicle . . . . A towed recreational vehicle
    is generally referred to as a “travel trailer.”
Board Decision at *3 (quoting J.A. 53 (Miller)).
    Probably the single most-popular class of towable
    RV is the Travel Trailer. Spanning 13 to 35 feet
    long, travel trailers are designed to be towed by
    cars, vans, and pickup trucks with only the addi-
    tion of a frame or bumper mounted hitch. Single
    axles are common, but dual and even triple axles
    may be found on larger units to carry the load.

(quoting J.A. 59 (Woodall’s)).
6                                                  IN RE: FOUGHT




     We conclude that the Board’s fact findings regarding
these references are not supported by substantial evidence.
The Board found that the Miller and Woodall’s distinction
of travel trailers from other recreational vehicles in terms
of towability is simply a statement of intended use. Board
Decision at *3–4. Second, the Board found that Miller’s ex-
planation that recreational vehicles and travel trailers
have living space rather than cargo space is a statement of
intended use. 

. These fact findings are not sup-
ported by substantial evidence. Towability is a structural
difference, not an intended use. A living area is likewise a
structural requirement.
    Based on the extrinsic evidence, we conclude that a
“travel trailer” is a specific type of recreational vehicle and
that this term is a structural limitation of the claims.
There is no dispute that if “travel trailer” is a limitation,
Dietrich and McDougal, which disclose cargo trailers and
shipping compartments, do not anticipate. Just as one
would not confuse a house with a warehouse, no one would
confuse a travel trailer with a truck trailer. We therefore
reverse and remand for further proceedings consistent
with this opinion.
                               II
     Appellants argue that the Board also erred because it
failed to explicitly state the level of ordinary skill in the art.
Appellants’ Br. 16–21. We do not agree. It is fundamental
that claims are interpreted “in light of the specification as
it would be interpreted by one of ordinary skill in the art.”
Phillips v. AWH Corp., 

, 1316 (Fed. Cir.
2005). Unless the patentee places the level of ordinary skill
in the art in dispute and explains with particularity how
the dispute would alter the outcome, neither the Board nor
the examiner need articulate the level of ordinary skill in
the art. We assume a proper determination of the level of
ordinary skill in the art as required by Phillips. Here, Ap-
pellants do not argue with any specificity that the level of
IN RE: FOUGHT                                              7



ordinary skill in the art would change the result. Instead,
they raise a generalized challenge to the Board’s decision
because it did not specifically articulate the level of ordi-
nary skill in the art. We find this challenge to be without
merit.
                       CONCLUSION
    For the foregoing reasons, we reverse and remand.
            REVERSED AND REMANDED
                           COSTS
    No costs.