       NOTE: This disposition is nonprecedential.


  United States Court of Appeals
      for the Federal Circuit
                ______________________

       CAPITAL SECURITY SYSTEMS, INC.,
               Plaintiff-Appellant

                           v.

 NCR CORPORATION, SUNTRUST BANKS, INC.,
           SUNTRUST BANK,
           Defendants-Appellees
          ______________________

                      2017-2368
                ______________________

   Appeal from the United States District Court for the
Northern District of Georgia in No. 1:14-cv-01516-WSD,
Judge William S. Duffey, Jr.
                ______________________

                Decided: March 7, 2018
                ______________________

    PETER LAMBRIANAKOS, Brown Rudnick, LLP, New
York, NY, argued for plaintiff-appellant. Also represent-
ed by ALFRED ROSS FABRICANT.

    PAUL WHITFIELD HUGHES, Mayer Brown LLP, Wash-
ington, district court, argued for defendants-appellees.
Also represented by STEPHEN ERIC BASKIN, JONATHAN
WEINBERG.
2        CAPITAL SECURITY SYSTEMS, INC.   v. NCR CORPORATION



                  ______________________

      Before PROST, Chief Judge, MOORE and STOLL,
                     Circuit Judges.
STOLL, Circuit Judge.
     Capital Security Systems, Inc. filed a patent in-
fringement action against NCR Corporation and other
defendants in the U.S. District Court for the Northern
District of Georgia, asserting infringement of U.S. Patent
Nos. 5,897,625; 7,653,600; 7,991,696; and 8,121,948. The
district court granted summary judgment of invalidity,
holding indefinite the term 1) “ascertains an apparent
signature” in claim 1 of the ’600 patent, claim 1 of the ’696
patent, and claims 1 and 2 of the ’948 patent; and 2)
“transactional operator” in claim 15 of the ’625 patent.
We reverse the district court’s determination that the
term “ascertains an apparent signature” is indefinite, we
affirm the district court’s determination that the term
“transactional operator” is indefinite, and we remand to
the district court for further proceedings consistent with
this opinion.
                        BACKGROUND
                             I.
    The patents asserted by Capital Security are directed
to an automated document cashing machine. See, e.g.,
’625 patent col. 3 ll. 57–58. The ’600, ’696, and ’948 pa-
tents (“the continuation patents”) share a common specifi-
cation and each claim priority to the parent ’625 patent.
    The parent ’625 patent purports to “[increase] the
profitability of the ATMs” by disclosing an “ATM-like
machine that performs and allows a number of service
options, such as for example the withdrawing of cash, the
depositing of cash, the cashing of a check, the cashing of a
money order, the buying of a money order, the transfer-
CAPITAL SECURITY SYSTEMS, INC.   v. NCR CORPORATION        3



ring of funds by wire, paying a bill and purchasing of end
user items.” Id. at col. 1 ll. 27–28, col. 3 ll. 57–63. The
continuation patents likewise describe “an automated
machine that cashes monetary transaction documents
such as checks, money orders, and that makes deposit
entries into the bank account of the user after validation
of the user and monetary transaction document, without
the aid of a bank teller.” ’600 patent, Abstract.
          A. “ascertains an apparent signature”
    The term “ascertains an apparent signature” is recit-
ed in the independent claims of the continuation patents.
Although the term appears in slightly different forms in
the different continuation patents, i.e., “ascertaining . . .
an apparent signature” (the ’696 patent) and “ascertain
an apparent signature” (the ’948 patent), the differences
are negligible for purposes of this appeal. Claim 1 of the
’600 patent is illustrative:
        1. An automated machine for an automated
    document handling system for making bank de-
    posits with a monetary document comprising:
        a card reader for a card having an intelli-
        gence associated therewith for identifying
        a system user as a qualified user;
        a document scanner for scanning the mon-
        etary document;
        a processor for receiving input from the
        document scanner and generating an im-
        age thereof;
        a document reader in the machine for the
        monetary document from which a deposit
        is being made;
        a display device coupled to the processor
        for displaying the image from the scanned
4         CAPITAL SECURITY SYSTEMS, INC.   v. NCR CORPORATION



        monetary document to the system user;
        and
        an acceptance of deposit indicator opera-
        ble by the processor after qualification of
        the user and validity of the document to
        indicate proof of deposit to the system us-
        er,
    wherein the processor reviews images from a legal
    amount recognition (LAR) line and a courtesy
    amount recognition (CAR) line and ascertains an
    apparent signature from the document image in
    order to validate the document.
’600 patent col. 39 l. 35 – col. 40 l. 11 (emphasis added).
    In connection with the disputed term, the specifica-
tion of the ’600 patent provides the following description:
    In accordance with a further aspect of the inven-
    tion, the bank will receive a validation that a sig-
    nature is present at the signature line of the
    document, such as a check, before performing the
    requested financial transaction with respect to the
    check. To this end, the signature line is located
    and an analysis is made to an acceptable confi-
    dence level that a signature is present at the sig-
    nature line. If a signature is lacking, the check
    will be rejected. Preferably, an analysis will be
    made as to verify the user’s signature against
    stored user signatures to provide an additional se-
    curity check to provide further confidence to the
    bank doing the transaction. Machine protection
    against a skilled forgery is difficult with current
    technology; nonetheless, unskilled forgeries or
    ambiguous signatures may still be detected.
Id. at col. 4 ll. 39–52.
CAPITAL SECURITY SYSTEMS, INC.   v. NCR CORPORATION    5



               B. “transactional operator”
    The term “transactional operator” is recited in claim
15 of the parent ’625 patent:
      15. An automated banking system for receiv-
   ing cash from a user and for dispensing cash to a
   user comprising:
       an automated machine having a card re-
       ceiver for receiving a card which identifies
       a user as being qualified to use the ma-
       chine;
       a document receiver for receiving a docu-
       ment to be cashed;
       a reader for reading the document for the
       amount and for a valid signature of the
       user if cash is to be dispensed to the user;
       a cash dispenser in the automated ma-
       chine for dispensing cash to the user oper-
       able upon an accepted reading by the
       reader;
       a cash receiver for receiving cash and for
       analyzing the amount of cash received
       from the user;
       a cash storage in the machine for receiving
       the cash being deposited by the user; and
       a transactional operator for operation by
       the user to perform a transaction upon
       deposit of sufficient cash by user for the
       requested transaction.
’625 patent col. 24 ll. 31–53 (emphasis added).
    The ’625 patent specification does not use the term
“transactional operator.”   It does, however, describe
“keypads 26 and 27” on the machine that a user can
6         CAPITAL SECURITY SYSTEMS, INC.   v. NCR CORPORATION



operate to perform a transaction option displayed to the
user. Specifically, the specification teaches a display
screen 20 which displays transaction options to a user
including “1) withdraw; 2) deposit; 3) cash check; 4) cash
money order; 5) buy money order; 6) wire transfer; 7) bill
payments; 8) purchase.” Id. at col. 10 ll. 3–8. The display
20 is “adjacent a pair of flanking additional keypads 26
and 27” with “arrow keys” “aligned with these options 1-
8.” See id. at col. 10 ll. 9–11. A user may depress one of
the arrow keys to perform one of the displayed transac-
tion options. Id. at col. 10 ll. 8–16.
   The specification also teaches a computer within the
machine that responds to input signals and executes
commands. Specifically:
    The user keyboard 18 supplies command signals
    to a microcomputer 21, in this embodiment a 133
    Mhz Pentium-based personal computer having a
    2.1 gigabyte hard disk drive for storing software, a
    32 megabyte random access memory for storing
    instructions and operands, a 133 Mhz Pentium
    microprocessor, an ISA bus, a PCI bus, a serial in-
    terface, and a parallel interface. (FIG. 3). The mi-
    crocomputer 21 executes application software
    under Windows 95, which among other things, re-
    sponds to keystrokes on the user keyboard 18, and
    signals from other input devices as set forth be-
    low. The microcomputer 21 drives the output dis-
    play 20 in response to the software it is executing
    and the various signals it receives from the input
    devices connected to transfer signals to it.
Id. at col. 8 ll. 43–56.
                            II.
    Prior to granting summary judgment of indefinite-
ness, the district court issued a claim construction order.
In the order, the court determined that NCR failed, at the
CAPITAL SECURITY SYSTEMS, INC.   v. NCR CORPORATION        7



Markman stage, to establish indefiniteness of the two
disputed terms by clear and convincing evidence, and
construed both terms. Capital Sec. Sys., Inc. v. NCR
Corp., No. 1:14-CV-1516-WSD, 2016 WL 3517595, at *5
(N.D. Ga. June 28, 2016). The court noted that “NCR
[did] not provide any expert testimony, prior art, or other
evidence to show that a person skilled in the art would be
unable to ascertain, with reasonable certainty, the scope
of the invention.” Id. The court added, however, that it
construed the terms “without prejudice” to NCR’s ability
to challenge the validity of the claims for indefiniteness at
the summary judgment stage. Id. at *4.
     The court construed “ascertains an apparent signa-
ture” as “[discovering] the presence of a person’s cursive
signature in the signature field.” Id. at *5. The court
explained that its construction was “supported by the
differentiation of validating a signature from recognizing
the presence of a signature,” and that “the kind of signa-
ture that is the subject of the patents is a cursive one.”
Id. at *5 n.6. With respect to “transactional operator,” the
court construed the term as “[a] computer within an
automated banking system that, after deposit of sufficient
cash, permits the user to perform the requested transac-
tion.” Id. at *6.
    NCR subsequently filed a motion for summary judg-
ment of invalidity asserting, among other things, that
these two terms were indefinite. The district court, after
considering competing testimony from Capital Security’s
expert, Dr. Bajaj, and NCR’s expert, Dr. Chatterjee,
granted summary judgment of indefiniteness. See Capital
Sec. Sys., Inc. v. NCR Corp., 263 F. Supp. 3d 1366, 1375
(N.D. Ga. 2017).
    In analyzing “ascertains an apparent signature,” the
district court credited Dr. Chatterjee’s testimony and
found Dr. Bajaj’s competing testimony conclusory and not
supported by “any reasoning or evidence.” Id. at 1372. In
8        CAPITAL SECURITY SYSTEMS, INC.   v. NCR CORPORATION



particular, the court agreed with Dr. Chatterjee’s testi-
mony that:
    [a] skilled artisan would not have been able to de-
    cide amongst four different plausible meanings of
    “apparent signature”: (1) determining if anything
    in the way of a mark was present in the signature
    field, useful or otherwise; (2) distinguishing a
    mark resembling legible text from a mark never
    intended to be a signature, such as a scratch or
    smudge mark; (3) determining if the scanned im-
    age field corresponds to a handwritten cursive
    signature versus an otherwise legitimate block
    letter printed name; or (4) determining if the sig-
    nature is forged.
Id. at 1373.
    The court was unpersuaded by NCR’s argument that
Dr. Chatterjee’s testimony merely shows that the term is
broad, not indefinite. The court explained that “Dr.
Chatterjee’s opinion is not that the term is broad enough
to encompass the four possibilities he set forth, but that a
skilled artisan would not be able to decide whether the
term encompasses all four examples or some subset of
them.” Id. at 1372.
    Regarding “transactional operator,” the court found
Dr. Bajaj’s testimony—that one of ordinary skill in the art
would understand that a computer included in an auto-
mated banking system is the “transactional operator”—
unsupported by any reasoning or evidence, and again
credited Dr. Chatterjee’s competing testimony. Specifical-
ly, Dr. Chatterjee testified that one of ordinary skill in the
art would be unable to determine the scope of “transac-
tional operator.” He opined that “transactional operator”
could be any of (1) a user interface allowing user selec-
tions; (2) an internal computer component like software
executing an algorithm; or (3) a computer component that
performs the task of “a bill reader [that] reads the provid-
CAPITAL SECURITY SYSTEMS, INC.   v. NCR CORPORATION        9



er’s account number and the user’s identification from the
bill” as in the transaction in Claim 17, and could include
“various input devices such as user keyboards, touch
screen, and auxiliary user input devices.” Id. at 1374.
The court concluded that “[a] person of ordinary skill in
the art, informed by the specification and the prosecution
history, would not be apprised with reasonable certainty
about the scope of the invention.” Id. at 1375.
   Capital Security timely appealed to this court.       We
have jurisdiction under 28 U.S.C. § 1295(a)(1).
                        DISCUSSION
     We review de novo a district court’s determination of
indefiniteness, and we review for clear error any of the
district court’s underlying findings of fact based on extrin-
sic evidence. MasterMine Software, Inc. v. Microsoft
Corp., 874 F.3d 1307, 1312–13 (Fed. Cir. 2017). A patent
claim must “particularly point[] out and distinctly claim[]
the subject matter which the applicant regards as his
invention.” 35 U.S.C. § 112, ¶ 2. “[A] patent is invalid for
indefiniteness if its claims, read in light of the specifica-
tion delineating the patent, and the prosecution history,
fail to inform, with reasonable certainty, those skilled in
the art about the scope of the invention.” Nautilus, Inc. v.
Biosig Instruments, Inc., 134 S. Ct. 2120, 2124 (2014).
          I.   “ascertains an apparent signature”
    NCR argues that, although the term “ascertains an
apparent signature” does not appear verbatim in the
specification, the term is not indefinite when considered
in the context of the claims and the specification. We
agree.
    Claim 1 of the ’600 patent recites a processor that “re-
views images from a legal amount recognition (LAR) line
and a courtesy amount recognition (CAR) line” of a
scanned monetary document (e.g., check) and “ascertains
an apparent signature from the document image in order
10       CAPITAL SECURITY SYSTEMS, INC.   v. NCR CORPORATION



to validate the document.” Read in the context of this
surrounding claim language, “ascertain[ing] an apparent
signature” seems to require, consistent with the ordinary
meaning of the claim language, determining the presence
of what appears to be a signature. This is consistent with
the specification.
    The specification explains that the automated ma-
chine determines whether “a signature is present at the
signature line of the document.” ’600 patent col. 4 ll. 40–
41. Specifically, the invention accomplishes this by first
locating the signature line, then analyzing “to an accepta-
ble confidence level that a signature is present at the
signature line.” Id. at col. 4 ll. 43–45. Thus, a skilled
artisan would understand the claimed ascertaining step
to correspond to determining the presence of a signature
on the signature line of a check, while acknowledging that
such a determination cannot be made with complete
certainty.
     The district court held “ascertains an apparent signa-
ture” indefinite principally because one of ordinary skill
could implement it in any, all, or a subset, of the four
different ways suggested by Dr. Chatterjee. Capital Sec.
Sys., 263 F. Supp. 3d at 1372–73. The four implementa-
tions suggested by Dr. Chatterjee, however, fall within a
reasonable range of implementations permitted by the
broad claim language as understood in light of the specifi-
cation. The specification discloses that, based on the
particular desired confidence level implemented in the
system, a check may be accepted unless (1) “a signature is
lacking,” ’600 patent col. 4 ll. 45–46; or (2) the signature
does not pass verification against a stored signature “to
provide an additional security check to provide further
confidence,” id. at col. 4 ll. 46–49. Given this disclosure in
the specification, we conclude that one of ordinary skill in
the art would understand, with reasonable certainty, the
scope of “ascertains an apparent signature” to include all
four implementations.
CAPITAL SECURITY SYSTEMS, INC.   v. NCR CORPORATION        11



    Citing, inter alia, Datamize, LLC v. Plumtree Soft-
ware, Inc., 417 F.3d 1342, 1350 (Fed. Cir. 2005), and
Interval Licensing LLC v. AOL, Inc., 766 F.3d 1364, 1371
(Fed. Cir. 2014), NCR argues that “ascertain[ing] an
apparent signature” is indefinite because it lacks any
objective standard of measure.      Appellee Br. 18–21.
Unlike the terms determined to be indefinite in the cases
relied on by NCR, however, the scope of the claimed
ascertaining step does not depend on the “unrestrained,
subjective opinion of a particular individual,” Datamize,
417 F.3d at 1350 (determining “aesthetically pleasing” to
be indefinite), and is not subject to the “unpredictable
vagaries of any one person’s opinion,” Interval Licensing,
766 F.3d at 1374 (determining “unobtrusive manner” to
be indefinite).
    NCR also analogized “[ascertaining] an apparent sig-
nature” to the term “block-like,” which was held indefinite
in In re Walter, 698 F. App’x 1022, 1027 (Fed. Cir. 2017).
In In re Walter, however, the term “block-like” was held
indefinite in view of applicant’s “erratic” statements made
during prosecution that defined the term in “inconsistent”
ways. Id. at 1025, 27. In particular, the applicant sug-
gested during prosecution that “block-like” could encom-
pass any material with flat sides, or even discreet pieces
conjoined “in some manner.” Id. at 1027. Here, on the
other hand, Capital Security did not muddle the scope of
“ascertains an apparent signature” during prosecution or
otherwise. Accordingly, we do not conclude that the term
“ascertains an apparent signature” is indefinite.
    We agree with the claim construction adopted by the
district court with one exception: we would remove the
“cursive” limitation. Although the parent ’625 patent
specification describes a “cursive signature,” see, e.g., ’625
patent col. 4 ll. 10–11, the common specification of the
continuation patents does not. In fact, of the three in-
stances “cursive” appears in the specification, none of
them relate to a user’s signature. ’600 patent col. 5 ll. 20–
12        CAPITAL SECURITY SYSTEMS, INC.   v. NCR CORPORATION



22 (“[Account numbers] are difficult to locate and must be
precisely delineated from other adjacent typing, printing,
letter or cursive to allow the transaction to be accom-
plished.”); id. at col. 18 ll. 14–19 (“[T]he processor . . . will
also read the cursive legal amount (LAR) line . . .”); id. at
col. 27 ll. 45–49 (“[T]he area immediately surrounding
the bounding box . . . is analyzed to determine whether
portions of characters, cursive strokes or the like extend
outside the bounding box region.”). Thus, we find no
reason to limit “signature” to cursive. Accordingly, the
correct construction of the term “ascertains an apparent
signature” in the continuation patents is “to discover the
presence of a person’s signature in the signature field.”
                   II. “transactional operator”
     Capital Security next argues that the claims and spec-
ification inform those skilled in the art about the scope of
the “transactional operator” with reasonable certainty.
Specifically, Capital Security argues that column 8, lines
43–56 of the ’625 patent specification describes an “em-
bodiment of a transactional operator.” Appellant Br. 22.
Consistent with this argument, Dr. Bajaj testified that
one of ordinary skill in the art would understand “a
computer included in an automated banking system” to be
one that, “after deposit of sufficient cash, permits the user
to perform the requested operation.” J.A. 2840. Dr. Bajaj
explained that the claimed operations “would include
options such as ‘withdraw,’ ‘deposit,’ and ‘cash check’ as
described in Figure 9.” Id.
    The passage relied on by Capital Security describes a
microcomputer 21 that “responds to keystrokes on the
user keyboard 18” and “signals from other inputs devices.”
’625 patent col. 8 ll. 52–53. It also explains that micro-
computer 21 “drives the output display 20 in response to
the software it is executing and the various signals it
receives from the input devices connected to transfer
signals to it.” Id. at col. 8 ll. 53–56. It is unclear from this
CAPITAL SECURITY SYSTEMS, INC.   v. NCR CORPORATION       13



passage, however, whether the computer or “transactional
operator” includes the microcomputer 21, the keyboard
18, and the display 20, or a subset thereof. It is also
unclear why the “transactional operator” does not include
the keypads 26 and 27 described in column 10 of the
specification, which a user depresses to perform a trans-
action option.
    This uncertainty is compounded by Capital Security’s
representations during oral argument. When asked about
the scope of the term during oral argument, Capital
Security indicated that it includes the keyboard described
in the passage, but not the display described in the same
passage. Oral Arg. at 12:12–13:29, http://oralarguments.
cafc.uscourts.gov/default.aspx?fl=2017-2368.mp3. Capital
Security did not explain why the “transactional operator”
would include keyboard 18, but not display 20, which
displays the transaction options to a user. Nor did Capi-
tal Security explain why “transactional operator” would
include keyboard 18, but not keypads 26 and 27, which a
user depresses to perform a transaction option.
    Indeed, we find no rationale supporting the seemingly
arbitrary definition of “transactional operator” as a mi-
croprocessor and keyboard, while excluding the associated
display and keypads. Because “transactional operator”
has no commonly-accepted definition and its scope is
unclear in view of the intrinsic evidence and Capital
Security’s proposed construction, we agree with the
district court that this term indefinite.
                       CONCLUSION
     We have considered the parties’ remaining arguments
and find them unpersuasive. Thus, we reverse the dis-
trict court’s determination that “ascertains an apparent
signature” in claim 1 of the ’600 patent, claim 1 of the ’696
patent, and claims 1 and 2 of the ’948 patent, is indefinite,
and we affirm the district court’s determination that
“transactional operator” in claim 15 of the ’625 patent is
14        CAPITAL SECURITY SYSTEMS, INC.   v. NCR CORPORATION



indefinite. Accordingly, we remand to the district court
for further proceedings consistent with this opinion.
 AFFIRMED-IN-PART, REVERSED-IN-PART, AND
               REMANDED
                           COSTS
     No costs.
