  United States Court of Appeals
      for the Federal Circuit
                ______________________

          REG SYNTHETIC FUELS, LLC,
                  Appellant

                          v.

                  NESTE OIL OYJ,
                       Appellee
                ______________________

                      2015-1773
                ______________________

    Appeal from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in No. IPR2013-
00578.
                 ______________________

              Decided: November 8, 2016
               ______________________

   JEAN MARIE GILLS, Foley & Lardner LLP, Chicago, IL,
argued for appellant. Also represented by MICHAEL
ROBERT HOUSTON.

    MICHAEL J. FLIBBERT, Finnegan, Henderson,
Farabow, Garrett & Dunner, LLP, argued for appellee.
Also represented by MAUREEN DONOVAN QUELER, KRISTI
L. MCINTYRE.
                ______________________

 Before PROST, Chief Judge, TARANTO, and CHEN, Circuit
                        Judges.
2                 REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ



CHEN, Circuit Judge.
    This appeal arises from a petition for inter partes re-
view filed by Neste Oil Oyj (Neste) against claims 1–5 and
8 of U.S. Patent No. 8,231,804 (’804 patent), which is
owned by REG Synthetic Fuels, LLC (REG). The United
States Patent and Trademark Office, Patent Trial and
Appeal Board (Board) instituted trial, and in its final
written decision, the Board found claims 1, 3, 4, and 8
anticipated by U.S. Patent No. 4,992,605 (Craig), and
claims 1–3, 5, and 8 anticipated by U.S. Published Patent
Application No. 2008/0312480 (Dindi). Neste Oil Oyj v.
REG Synthetic Fuels, LLC, No. IPR2013-00578, 2015 WL
1263029, at *14, 17 (PTAB Mar. 12, 2015). During trial,
both parties filed motions to exclude documentary evi-
dence, and the Board excluded several REG exhibits
based on hearsay and other grounds. REG appeals the
Board’s unpatentability determinations and its exclusion
of certain REG exhibits. For the reasons stated herein,
we affirm-in-part, reverse-in-part, vacate-in-part, and
remand for further proceedings.
                       BACKGROUND
    The ’804 patent is directed to paraffin compositions
containing primarily even-carbon-number paraffins and
methods of making them. Paraffins are hydrocarbon
chains that contain carbon and hydrogen atoms, and
even-carbon-number paraffins are saturated hydrocarbon
chains with the general chemical formula CnH2n+2, 1 in
which the “n” is an even number.
   Even-carbon-number paraffins are useful as phase
change materials (PCMs), which can be used as insulation


    1  The parties use Cn or Cn as a shorthand for
CnH2n+2. These notations refer to the same hydrocarbon
chain.
REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ                 3



in a house because they can absorb heat during the warm
portions of the day by undergoing a solid-liquid phase
transition and return the heat during the cooler portions
of the day by re-freezing. The thermal storage capacity of
PCMs is determined by their latent heat of fusion, which
is higher for even-carbon-number paraffins than for odd-
carbon-number paraffins. The ’804 patent seeks to in-
crease the production of compositions with higher per-
centages of even-carbon-number paraffins. One method
disclosed in the ’804 patent is the hydrogenation and
deoxygenation of naturally occurring fatty acids and
esters, such as bio-oils, to produce primarily even-carbon-
number paraffins.
   Claim 1 is representative for purposes of this appeal:
   1. A phase change material composition compris-
   ing at least 75 wt% even carbon number paraffins,
   wherein the paraffins are produced by hydrogena-
   tion/hydrogenolysis of naturally occurring fatty
   acids and esters.
    During trial, the Board provided several claim con-
structions, none of which are being appealed. It first
found that the preamble of claim 1 was not limiting
because the term “phase change material composition”
expressed only an intended use, and did not limit the
scope of the claim. It also found that the process of pro-
duction (i.e., producing paraffins by “hydrogena-
tion/hydrogenolysis of naturally occurring fatty acids and
esters”) was not limiting. Because the Board found that
the term “phase change material composition,” and the
process of production were not limiting, and neither party
challenges these constructions, we accept them. The key
limitation for purposes of this appeal is the “at least 75
wt% even carbon number paraffins” limitation. The
“wt%” limitation describes the percentage concentration,
in units of weight percent, of even-carbon-number to odd-
carbon-number paraffins in the claimed composition.
4                 REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ



    Claim 2 depends on claim 1, and it further recites that
the composition comprises at least 80 wt% even-carbon-
number paraffins. Claims 3–5 depend on claim 1, and
they recite specific numbers of carbons. Claim 8 depends
on claim 1 and recites the presence of a catalyst.
    Neste requested inter partes review of claims 1–5 and
8 of the ’804 patent in September 2013. The Board insti-
tuted trial in March 2014, based on a reasonable likeli-
hood of finding that Dindi and Craig anticipated the
claims.
    In its final decision, the Board found that Craig antic-
ipated claims 1, 3, 4, and 8 because Craig disclosed a
process for producing hydrocarbon products in the diesel
boiling range (C15H32 through C18H38) that are effective in
improving diesel fuel ignition. Craig disclosed hydrocar-
bon products obtained from naturally occurring feed-
stocks, and the results of a gas chromatography mass
spectrometry (GC-MS) analysis of the products, shown as
peak area percentages for each hydrocarbon. Although
Craig did not disclose weight percentages, the Board
found that Craig anticipated claims 1, 3, 4, and 8 because
a person of ordinary skill in the art could readily convert
the disclosed peak area percentages into their correspond-
ing weight percentages, and the sum of the converted
peak area percentages of Craig met the claim requirement
that the overall weight percentage of even-carbon-number
paraffins be at least 75 wt%.
    The Board also found that Dindi anticipated claims 1–
3, 5, and 8 because Dindi described a process for convert-
ing renewable resources, such as vegetable oil and animal
fat, into paraffins, in which a renewable resource is
processed using hydrogen and a molybdenum catalyst to
produce a hydrocarbon product with a ratio of even-
REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ               5



carbon-numbered to odd-carbon-numbered hydrocarbons
of at least 2:1. 2 At trial, REG sought to introduce certain
exhibits to establish an earlier invention date that pre-
dated Dindi’s filing date. These exhibits included, for
example, test data from third parties, communications
between REG’s inventor, Mr. Abhari, and third parties on
the invention and the test data, and minutes from meet-
ings that Mr. Abhari had attended. Neste moved to
exclude, and the Board agreed to exclude, these REG
exhibits based on lack of authentication, hearsay, or
improper reply evidence. REG contends that these exhib-
its show the mental thoughts of Mr. Abhari and that he
communicated his invention to third parties prior to
Dindi’s filing date.
    The Board issued its final written decision on March
12, 2015, finding that Neste established by a preponder-
ance of evidence that Craig and Dindi anticipated all of
the challenged claims. On appeal, REG challenges the
Board’s anticipation findings, and its rulings on REG’s
excluded exhibits. REG argues that Craig cannot antici-
pate claims 1, 3, 4, and 8 because Craig discloses area
percentages rather than weight percentages, and that
Dindi cannot anticipate claims 1–3, 5, and 8 because Mr.
Abhari invented the subject matter of the ’804 patent
before Dindi’s filing date. REG also argues that the
Board’s exclusion of its exhibits was prejudicial because
REG relied on them to show that Mr. Abhari recognized
and communicated his conception of the invention to a
third party before Dindi’s June 13, 2008 filing date.




   2    This ratio of at least 2:1 appears to be less than
75%, but the parties do not dispute that Dindi meets the
at least 75 wt% (and the at least 80 wt%) limitation for
purposes of this appeal.
6                 REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ



                         ANALYSIS
    We have jurisdiction over this appeal under 28 U.S.C.
§ 1295(a).
                   I. Standard of Review
    Anticipation is a question of fact, and decisions from
the Board on factual matters are reviewed for substantial
evidence. Eli Lilly & Co. v. Bd. of Regents of Univ. of
Wash., 334 F.3d 1264, 1267 (Fed. Cir. 2003).
    “Priority of invention and its constituent issues of
conception and reduction to practice are questions of law
predicated on subsidiary factual findings.” 3 Singh v.
Brake, 317 F.3d 1334, 1340 (Fed. Cir. 2003). Thus, we
“review de novo the Board’s legal conclusions with respect
to priority, conception, and reduction to practice.” Id. To
show prior invention, REG must “either prove (1) a con-
ception and reduction to practice before the filing date of
[Dindi] or (2) a conception before the filing date of [Dindi]
combined with diligence and reduction to practice after
that date.” Taurus IP, LLC v. DaimlerChrysler Corp.,
726 F.3d 1306, 1323 (Fed. Cir. 2013). In appeals from the
Board, corroboration is a subsidiary factual issue re-
viewed for substantial evidence. In re Gartside, 203 F.3d
1305, 1315 (Fed. Cir. 2000).




    3   “Congress amended 35 U.S.C. § 102 in 2011 as
part of the America Invents Act (‘AIA’).” Medicines Co. v.
Hospira, Inc., 827 F.3d 1363, 1372 n.1 (Fed. Cir. 2016) (en
banc) (citing Leahy-Smith America Invents Act, 125 Stat.
84, 341 (2011)). “References to § 102 . . . in this opinion
refer to the pre-AIA version of the statute, the version
that applies here” because the claims at issue have an
effective filing date prior to March 16, 2013. Id.
REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ              7



    We review the Board’s evidentiary rulings for abuse of
discretion. Chen v. Bouchard, 347 F.3d 1299, 1307 (Fed.
Cir. 2003).
                 II. Anticipation by Craig
    We begin with REG’s argument that Craig does not
anticipate claims 1, 3, 4, and 8 of the ’804 patent because
Craig discloses area percentages rather than weight
percentages.
     The Board determined that Table 9 of Craig discloses
naturally occurring feedstocks, including canola oil,
rapeseed oil, and palm oil, and the hydrocarbon products
produced from each of these feedstocks. Table 9 shows
the results of a GC-MS analysis of the hydrocarbon prod-
ucts produced by Craig, shown in peak area percentages
for each hydrocarbon, e.g., C16.
8                 REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ




    Table 9 discloses, for example, that hydrotreating
“Canola Oil, Premium Quantity, 210-343 ºC cut” results in
a hydrocarbon product with peak area percentages of
3.1% C16, 78.28% C18 and 1.38% C20. The Board noted
that the GC-MS area percentages do not by themselves
establish, by a preponderance of evidence, weight per-
centages within the claimed ranges of the ’804 patent.
The Board agreed, however, with Neste’s expert (Dr.
Klein) that a person of ordinary skill in the art could use
relative response factors to convert GC-MS area percent-
ages into weight percentages.
    REG argued to the Board that Craig does not provide
enough information to accurately convert the GC-MS
peak area percentages to weight percentages using rela-
tive response factors, but the Board disagreed. The Board
found that Dr. Klein’s Table 2 illustrated that Craig’s
Table 9 disclosed products containing even-carbon-
number paraffins sufficiently within the weight percent-
age range of 75 wt% recited in claim 1 of the ’804 patent.
REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ             9




    Table 2 shows Dr. Klein’s calculation of the weight
percentages for various feedstocks from Craig’s Table 9,
using three sets of relative response factors, which Dr.
Klein obtained from the prior art references in the record
(Hsu, Göröcs, and Chaurasia). J.A. 1316. The Board
found that the lowest calculated weight for Canola Pre-
mium, for instance, was 82.31 wt%, which was more than
7% higher than the 75 wt% recited in claim 1 of the ’804
patent. Although Dr. Klein calculated different weight
percentages when he used each of the three relative
response factors, the differences in calculated wt% values
among the uses of the three relative response factors were
very small, as shown in Table 2. Thus, the Board found it
unlikely that any correction required by the experimental
conditions would result in a weight percentage of less
than the 75 wt% recited in claim 1. 4



   4   The Board found that Dr. Klein’s calculated val-
ues were too close to claim 2’s limitation of at least 80
wt% to conclude that Neste established, by a preponder-
10                REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ



    REG argues that the Board used an erroneous inher-
ency standard because the Board found it unlikely that
Craig did not disclose the claimed limitations of “weight
percentages.” REG believes that the Board relied on Dr.
Klein’s testimony to “fill the gap” in Craig by estimating
weight percentages using the area percentages of Craig,
and in REG’s view, this conversion is not so straightfor-
ward. REG points to evidence that converting weight and
area percentages requires calibration of the instrument to
account for actual instrument operating conditions. Dr.
Klein did not perform this calibration, and instead used
several different estimates to suggest precision. REG
contends that precision does not mean accuracy, absent
calibration.
    Neste responds that the Board did not use inherency
because Craig expressly discloses the concentration of
even-carbon-number paraffins in area percentages. Neste
argues that substantial evidence supports the Board’s
finding that a person of ordinary skill could readily con-
vert Craig’s area percentages to the weight percentages
recited in the claims using Dr. Klein’s calculations.
    We agree with Neste. Dr. Klein converted the area
percentages of Craig into the weight percentages recited
in the ’804 patent using several different relative re-
sponse factors from the prior art, including Göröcs and
Chaurasia, which REG’s own expert, Dr. Lamb, cited in
his expert declaration. J.A. 2895–98. Dr. Lamb agreed
that relative response factors could be used to convert
area percentages to weight percentages, and that Göröcs
and Chaurasia disclosed that response factors increase
linearly with carbon number, but he concluded that Craig


ance of the evidence, that Table 9 discloses compounds
within the scope of claim 2. Neste does not appeal this
finding.
REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ             11



did not provide any calibration data or other indicia of
reliability. 5 J.A.2897–98. This is not an inherency issue,
however, because the challenged limitation is not missing
from Craig. See Cont’l Can Co. USA v. Monsanto Co., 948
F.2d 1264, 1268 (Fed. Cir. 1991) (“To serve as an anticipa-
tion when the reference is silent about the asserted inher-
ent characteristic, such gap in the reference may be filled
with recourse to extrinsic evidence.”). Craig is not silent
as to the concentration of even-carbon-number paraffins
because it expressly discloses this concentration in area
percentage. Dr. Klein simply converted one unit of meas-
urement (area percent) into another unit of measurement
(weight percent) by using relative response factors from
the prior art. Dr. Klein explained that this conversion
was a reliable technique given the very similar weight
percentage results after using three different sets of
relative response factors. J.A. 1309–17. On this record,


   5    At oral argument, REG agreed that its argument
to predate the Dindi reference relied on exhibits that
show area percents rather than weight percents. REG
concluded, however, that the essential distinction was
that Craig used a GC-MS detector, whereas Mr. Abhari
used a gas chromatography analyzer with flame ioniza-
tion detector (GC-FID). REG’s expert Dr. Lamb testified
that unlike for a GC-MS detector, a paraffin’s weight
percent can be reliably calculated from the GC-FID area
percent and the relative response factor for that paraffin
because GC-FID response factors for paraffins in the C14-
C22 range are equivalent within ~1%. J.A. 2895–98.
Neste responded that per Dr. Klein’s testimony, a person
of ordinary skill in the art would have readily recognized
that quantitative data from a GC-MS detector could be
reliably converted to weight percentages using the rela-
tive response factors, and weight percentages were all
that the claims required. J.A. 1309–17.
12                REG SYNTHETIC FUELS, LLC    v. NESTE OIL OYJ



substantial evidence supports the Board’s factual finding
that the area percent disclosed in Craig could be reliably
translated to the weight percent recited in the ’804 pa-
tent.
    REG argues that Chaurasia discloses an average er-
ror of 3–5% with a range of +/- 20% of the observed val-
ues. This error range, however, does not arise from
Chaurasia’s own analysis, but it is Chaurasia’s descrip-
tion of an error range from a separate study by Fitch and
Sauter, i.e., it is a reference within a reference. Fitch and
Sauter itself is not part of the record. Furthermore, the
Fitch and Sauter error range applies to the calculation of
the atomic or molecular cross-section of a specific mole-
cule, not the percentage concentration of even-to-odd
carbon number paraffins in a mixture of paraffins. An-
other distinction is that Fitch and Sauter’s error range
applies to polycyclic aromatic hydrocarbons and polychlo-
rinated biphenyl products (i.e., they contain chlorine,
phenyl, and other pollutants), which are more complex
molecules than the even-carbon-number paraffins (i.e.,
linear straight chain alkanes containing only carbons and
hydrogens) at issue in this case. Thus, REG fails to
establish that the error range of Fitch and Sauter is
applicable to Dr. Klein’s calculations.
    In view of the foregoing, we affirm the Board’s finding
that Craig anticipates claims 1, 3, 4 and 8 of the ’804
patent.
                 III. Anticipation by Dindi
    Because claims 2 and 5 of the ’804 patent remain at
issue, we must still address REG’s arguments with re-
spect to anticipation of claims 2 and 5 by Dindi. Claim 2
depends on claim 1, and recites that the composition
comprises at least 80 wt% even-carbon-number paraffins.
Claim 5 depends on claim 1, and it recites that the even-
carbon-number paraffins include n-dodecane and n-
tetradecane.
REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ               13



     REG argued before the Board that Dindi was not prior
art to the ’804 patent because Mr. Abhari invented the
subject matter of the ’804 patent before the June 13, 2008
filing date of Dindi. The Board recognized that to ante-
date Dindi, REG had to “prove (1) a conception and reduc-
tion to practice before the filing date of [Dindi] or (2) a
conception before the filing date of [Dindi] combined with
diligence and reduction to practice after that date.”
Taurus IP, 726 F.3d at 1323. In either case, REG had to
prove conception prior to the June 13, 2008 filing date of
Dindi. Id.
    Conception is “the formation, in the mind of the in-
ventor of a definite and permanent idea of the complete
and operative invention, as it is thereafter to be applied in
practice.” Coleman v. Dines, 754 F.2d 353, 359 (Fed. Cir.
1985) (emphasis in original) (quoting Gunter v. Stream,
573 F.2d 77, 80 (C.C.P.A. 1978)). Conception must in-
clude every feature or limitation of the claimed invention.
Davis v. Reddy, 620 F.2d 885, 889 (C.C.P.A. 1980). “Con-
ception must be proved by corroborating evidence which
shows that the inventor disclosed to others his ‘completed
thought expressed in such clear terms as to enable those
skilled in the art’ to make the invention.” Coleman, 754
F.2d at 359 (quoting Field v. Knowles, 183 F.2d 593, 600
(C.C.P.A. 1950)). However, “there is no final single for-
mula that must be followed in proving corroboration.”
Kridl v. McCormick, 105 F.3d 1446, 1450 (Fed. Cir. 1997)
(quoting Berry v. Webb, 412 F.2d 261, 266 (C.C.P.A.
1969)).
    We agree with REG that it has proven conception pri-
or to the filing date of Dindi, based on Exhibits 2011 and
2058, both already admitted in evidence, and the content
of Exhibit 2061, which the Board incorrectly excluded
from evidence based on hearsay. These three exhibits
provide documentary evidence that, by April 2008, Mr.
Abhari conceived of a definite and permanent idea of the
complete and operative invention, and that he had dis-
14                REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ



closed to a third party his complete thoughts in such clear
terms that the third party was able to make his invention
using his process.
    We first review the documentary evidence already
admitted in evidence. Exhibit 2011 contains an email
dated October 19, 2007 from Mr. Abhari to SwRI, a third
party, with an objective to “[c]onvert 1,200 gallons of bio-
feedstock to synthetic diesel product using SwRI’s large (2
gal/h) fixed-bed hydrogenation unit.” J.A. 2722. This
email discloses a process for making the invention be-
cause it contains instructions for the reaction conditions
and for conducting the sampling and analysis. Exhibit
2011 broadly describes Mr. Abhari’s process as a way to
produce synthetic diesel product, which is sufficient to
show that Mr. Abhari disclosed his completed thought to
SwRI in such clear terms as to enable SwRI to make the
invention. See Coleman, 754 F.2d at 359. We agree,
however, that Exhibit 2011 is not sufficient by itself to
show conception because it does not show that Mr. Abhari
knew that his process would create at least 75 wt% even-
carbon-number paraffins.
    We turn next to Exhibit 2058, also admitted in evi-
dence, which contains an email dated April 2, 2008 from
SwRI back to Mr. Abhari, describing the results of the
latest test runs. SwRI’s email expressly identifies one of
the test runs as Sample “084.” The GC data for Sample
“084” contains both a graph and a table showing peak
results with the following area percentages: C14 (1.218%),
C16 (21.926%), C18 (56.773%), and C20 (0.871%). J.A. 3454.
The sum of the area percentages for these four even-
carbon-number paraffins is 80.788%. Mr. Abhari quickly
replied to SwRI by email, inquiring about the results of a
second sample. J.A. 3443. SwRI responded that same
day, writing that the second sample contained area per-
centages of C16 (22%), C17 (11%), and C18 (55%).
REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ              15



     Taken together, Exhibits 2011 and 2058 disclose all
the limitations of claims 1 and 2 because Exhibit 2058
discloses a diesel product composition 6 that contained at
least 80 wt% even-carbon-number paraffins. 7 Exhibit
2011 shows that SwRI created the claimed composition
using a “hydrogenation” process of naturally occurring
fatty acids and esters, as recited by claim 1, because Mr.
Abhari sent an email to SwRI stating that the objective
was to convert “biofeedstock” to “diesel fuel,” using SwRI’s
“fixed-bed hydrogenation unit.” J.A. 2722. Mr. Abhari
knew that SwRI had created the composition because he
responded to SwRI’s email describing the results. He
disclosed his invention to others because Exhibit 2058
shows that SwRI made the composition using Mr. Abha-
ri’s instructions from Exhibit 2011.
     Neste argues that nothing in Exhibits 2011 and 2058
discloses the process that Mr. Abhari attempted to test.
This is incorrect because Exhibit 2011 shows that in
October 2007, Mr. Abhari emailed SwRI a description of a
process, and Exhibit 2058 shows that in April 2008, SwRI
emailed Mr. Abhari the results of that process. Neste
provides no reason to suggest that SwRI would not have
followed Mr. Abhari’s express instructions.
   Neste also asserts that nothing in Exhibits 2011 and
2058 shows that Mr. Abhari knew that the sum of the
weight percentages of the even-carbon-number paraffins
met claim 2’s limitation of “at least 80 wt%.” The sum of


   6   As noted earlier, the Board’s construction of claim
1 does not require the claimed composition to be a PCM
material, nor does it require the compositions to be made
by any particular process.
    7  Although Exhibit 2058 discloses area percentages
rather than weight percentages, Neste does not argue
that Exhibit 2058 is ineffective for that reason.
16                REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ



the four percentages for C14 (1.218%), C16 (21.926%), C18
(56.773%), and C20 (0.871%) is more than 80%, but it is
true that nothing from Mr. Abhari in Exhibits 2011 and
2058 expressly stated that the percentages of even-
carbon-number paraffins should be summed up or that
the sum of these percentages met claim 2’s limitation of
“at least 80 wt%.” This “knowledge” of Mr. Abhari is
supplied by Exhibit 2061, which contains an email dated
April 29, 2008 from Mr. Abhari to Microtek, another third
party who specialized in PCM materials, stating that he
could achieve an 80% purity C18 product. 8
    Exhibit 2061 is a set of two emails between Mr. Abha-
ri and Microtek. The first email is from Dawn Mantz of
Microtek to Mr. Abhari on March 6, 2008, in which Ms.
Mantz thanks Mr. Abhari for sending a sample and
informs Mr. Abhari that Microtek had already begun its
preliminary testing on the sample in the lab. The second
email is from Mr. Abhari to Amy Damewood and Ms.
Mantz on April 29, 2008, in which Mr. Abhari informs Ms.
Damewood and Ms. Mantz that he has “had more difficul-
ty than [he] expected trying to recover a 90+% purity
nC18 product using [his] lab distillation glassware (80%
purity C18 is the best [they] got).” J.A. 7868. Neste
argued before the Board that these emails were hearsay
because they contain out of court statements by Ms.
Mantz. REG responded that these emails were not hear-
say, because it did not offer the emails to prove the truth
of the matter asserted. Rather, REG contended that it
offered the emails to show that Mr. Abhari recognized the
usefulness of high even-carbon-number paraffins as a
PCM material and that he would not have otherwise



     8  Exhibit 2061 also discloses percentages rather
than weight percentages, but Neste does not argue that
Exhibit 2061 is ineffective for that reason.
REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ             17



contacted Microtek. The Board agreed with REG, in part,
finding that the fact that Mr. Abhari contacted Microtek
was a non-hearsay use of Exhibit 2061, and the Board
admitted Exhibit 2061 for that limited purpose. The
Board did not consider the content of Exhibit 2061, which
it found to be hearsay.
    We find that the Board erred to the extent that it ex-
cluded the content of Exhibit 2061 based on hearsay
because REG offered Exhibit 2061 for the non-hearsay
purpose to show that Mr. Abhari thought he had achieved
80 wt% purity C18 product. 9 The act of writing and send-
ing the email is, by itself, probative evidence on whether
Mr. Abhari recognized—at the time that he had written
the email—that the sum of the weight percentages of
even-carbon-number paraffins in his compositions was at
least 80 wt% and communicated this to a third party. In
Knorr v. Pearson, 671 F.2d 1368, 1372–73 (C.C.P.A. 1982),
the U.S. Court of Customs and Patent Appeals found that
a statement was not hearsay if “the communication (as
opposed to the truth) ha[d] legal significance.” Knorr
involved a telephone call, in which two co-inventors,
Buergin and Pearson, discussed an invention, and which
was overheard by a third party, Rutkowski. Id. at 1370.
The court held that Rutkowski’s testimony on what he
heard Buergin say to Pearson was not hearsay because
the communication of the idea had legal significance as
the basis for the conception of the invention. Id. at 1373–
74. By contrast, Rutkowski’s testimony on “Buergin’s
statements to Rutkowski regarding what Pearson said”
was hearsay. Id. at 1373.



   9    Neste did not challenge the authentication of Ex-
hibit 2061, J.A. 546, 552, so we infer that Exhibit 2061
accurately shows the communications between Mr. Abha-
ri and Microtek in March and April, 2008.
18                REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ



     Here, Knorr supports REG’s position that Mr. Abha-
ri’s communication with Microtek in Exhibit 2061 is
legally significant because it shows that Mr. Abhari
communicated the conception of his invention to a third
party, Microtek. Thus, the documentary evidence con-
tained in Exhibits 2011, 2058, and 2061 corroborate Mr.
Abhari’s conception of the claimed compositions as of
April 2008.     Exhibit 2011 shows that Mr. Abhari dis-
closed his process to a third party. Exhibit 2058 shows
that the third party produced the claimed compositions
using this process, and Exhibit 2061 shows that Mr.
Abhari recognized and communicated to a third party
that he could create a composition with the claimed
property of at least 80 wt% even-carbon-number paraf-
fins.
     The Board also found that it could not determine
from Exhibit 2061 the specific product or process that Mr.
Abhari had in mind, or the fact that Mr. Abhari had
recognized that he had created something new, when he
had emailed Microtek that he could achieve at least 80
wt% purity C18 product. Conception, however, does not
require that Mr. Abhari recognize that he created a PCM
material, or the specific process by which he had created
80 wt% purity C18 product, because the Board’s construc-
tion of the claims did not limit the invention based on
these features. The only feature at issue here is whether
Mr. Abhari disclosed a composition containing at least 80
wt% even-carbon-number paraffins to others, and we find
that he did. Mr. Abhari’s email to Microtek expressly
states that he could achieve at least 80% purity C18 prod-
uct, which was new in April 2008 because this product did
not exist in the prior art, given the record before us. Nor
does Neste dispute that Mr. Abhari sent this email to
Microtek because the Board admitted Exhibit 2061 to
show that Mr. Abhari contacted Microtek, which Neste
does not appeal.
REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ               19



     We reverse the Board’s findings on conception and its
exclusion of the contents of Exhibit 2061 based on hear-
say. We find that Exhibit 2061 shows that Mr. Abhari
“disclosed to others,” see Coleman, 754 F.2d at 359, a
composition including every feature or limitation of the
claimed invention, see Davis, 620 F.2d at 889. We also
find that, based on Exhibits 2011, 2058, and 2061, Mr.
Abhari’s disclosure was a “‘completed thought expressed
in such clear terms as to enable those skilled in the art’ to
make the invention.” Coleman, 754 F.2d at 359. Howev-
er, because the Board did not make factual findings on
diligence or reduction to practice in the first instance, we
remand for the Board to make these findings.
    REG also appeals the Board’s exclusion of Exhibits
2012, 2013, 2057 and 2062 based on hearsay. We do not
address these rulings because we find that Exhibits 2011,
2058 and 2061 are sufficient to show conception, but
because Exhibits 2012, 2013, 2057 and 2062 may be
relevant for diligence and reduction to practice, we vacate
the Board’s exclusion of these exhibits and remand for
further consideration consistent with this opinion.
    We have considered REG’s remaining arguments and
find no abuse of discretion in the Board’s decision to
exclude Exhibits 2003 and 2006 for lack of authentication.
We also find no abuse of discretion in its exclusion of
Exhibit 2053 for improper reply evidence. Our affirmance
of those exclusions should not be taken as necessarily
approving of all of the Board’s reasoning explaining the
exclusions.
                       CONCLUSION
    For the foregoing reasons, we affirm the Board’s de-
termination that Craig anticipates claims 1, 3, 4 and 8 of
the ’804 patent. However, we reverse the Board’s finding
that REG failed to establish conception of the invention
prior to Dindi’s filing date of June 13, 2008. Consequent-
ly, we vacate the Board’s finding of anticipation of claims
20                REG SYNTHETIC FUELS, LLC   v. NESTE OIL OYJ



2 and 5, and we remand for further fact finding on dili-
gence and reduction to practice.
    We reverse the Board’s determination to exclude Ex-
hibit 2061 for failure to consider its non-hearsay purpose.
We vacate the Board’s exclusion of Exhibits 2012, 2013,
2057 and 2062 for hearsay, and we affirm the Board’s
exclusion of Exhibits 2003, 2006 and 2053 based on lack
of authentication and improper reply evidence.
     AFFIRMED-IN-PART, REVERSED-IN-PART,
       VACATED-IN-PART, AND REMANDED
                          COSTS
     No costs.
