United States Court of Appeals
    for the Federal Circuit
           ______________________

TRADING TECHNOLOGIES INTERNATIONAL,
                  INC.,
           Plaintiff-Appellant,

                     v.

   OPEN E CRY, LLC, AND OPTIONSXPRESS
            HOLDINGS, INC.,
            Defendants-Appellees,

                    AND

   TRADESTATION SECURITIES, INC., AND
      TRADESTATION GROUP, INC.,
          Defendants-Appellees,

                    AND

   IBG, LLC, THINKORSWIM GROUP, INC.,
  TD AMERITRADE, INC., TD AMERITRADE
HOLDING CORP., AND INTERACTIVE BROKERS,
                    LLC,
             Defendants-Appellees,

                    AND

        CQG, INC., AND CQGT, LLC,
          Defendants-Appellees,

                    AND
2            TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC


         FUTUREPATH TRADING LLC,
        SUNGARD DATA SYSTEMS, INC.,
    SUNGARD INVESTMENT VENTURES LLC, AND
          GL TRADE AMERICAS, INC.,
              Defendants-Appellees,

                          AND

     STELLAR TRADING SYSTEMS, LTD., AND
       STELLAR TRADING SYSTEMS, INC.,
              Defendants-Appellees,

                          AND

             ESPEED MARKETS, LP,
         BGC CAPITAL MARKETS, LP, AND
               ECCOWARE LTD.,
               Defendants-Appellees,

                          AND

       ROSENTHAL COLLINS GROUP, LLC,
                   Defendant.
             ______________________

                      2012-1583
                ______________________

   Appeal from the United States District Court for the
Northern District of Illinois in consolidated No. 10-CV-
0715, Judge Virginia M. Kendall.
                ______________________

               Decided: August 30, 2013
               ______________________
TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC          3
    STEVEN F. BORSAND, Trading Technologies Interna-
tional, Inc., of Chicago, Illinois, argued for plaintiff-
appellant. Of counsel on the brief were LEIF R. SIGMOND,
JR., MICHAEL D. GANNON, PAUL A. KAFADAR, and SARAH E.
FENDRICK, McDonnell Boehnen Hulbert & Berghoff LLP,
of Chicago, Illinois. Of counsel were JENNIFER KURCZ and
MATTHEW SAMPSON.

    ANTHONY B. ULLMAN, Salans LLP, of New York, New
York, argued for all defendants-appellees. With him on
the brief for FuturePath Trading, LLC, et al., was LORA A.
MOFFATT. Of counsel on the brief were PHILIPPE BENNETT
and AOIFE BUTLER, Alston & Bird, LLP, of New York,
New York. On the brief for IBG, LLC, et al., were
MICHAEL BRETT LEVIN and CHRISTOPHER P. GREWE,
Wilson Sonsini Goodrich & Rosati, of Palo Alto, Califor-
nia, and NATALIE J. MORGAN, of San Diego, California.
On the brief for CQG, Inc., et al., were ADAM G. KELLY,
WILLIAM J. VOLLER, and J. SIMONE JONES, Loeb & Loeb,
LLP, of Chicago, Illinois. On the brief for eSpeed Mar-
kets, LP, et al., was GARY A. ROSEN, Law Offices of Gary
A. Rosen, P.C., of Ardmore, Pennsylvania. On the brief
for TradeStation Securities, Inc., et al., were DAVID J.
HEALEY, Fish & Richardson P.C., of Houston, Texas, and
ADAM KESSEL and KEVIN SU, of Boston, Massachusetts.

    SCOTT J. BORNSTEIN, Greenberg Traurig, LLP, of New
York, New York, for defendants-appellees Open E. Cry,
LLC, et al. With him on the brief was JAMES J. LUKAS,
JR., of Chicago, Illinois.

    LAURA A. LYDIGSEN, Brinks Hofer Gilson & Lione, of
Chicago, Illinois, for defendants-appellees, Stellar Trad-
ing Systems, Ltd., et al. Of counsel were RALPH J. GABRIC
and MARC V. RICHARDS.
                  ______________________
4             TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC
Before LOURIE and PLAGER, Circuit Judges, and BENSON,
                   District Judge.*
LOURIE, Circuit Judge.
     In this patent infringement action, Plaintiff-Appellant
Trading Technologies International, Inc. (“TT”) appeals
from the district court’s entry of summary judgment that
(i) the asserted claims of TT’s U.S. Patents 7,676,411 (the
“’411 patent”), 7,693,768 (the “’768 patent”), 7,904,374
(the “’374 patent”), and 7,685,055 (the “’055 patent”) are
invalid for failure to comply with the written description
requirement of 35 U.S.C. § 112; and (ii) prosecution
history estoppel bars TT from asserting the ’055 patent
against software products that include certain display
functions. The district court premised both holdings on
deference to our prior decision in Trading Technologies
International, Inc. v. eSpeed, Inc., 595 F.3d 1340 (Fed.
Cir. 2010) (“eSpeed”), which considered two related pa-
tents from TT’s portfolio.
     We conclude that eSpeed does not control the issues
presented in this appeal, and the district court’s rulings
based on that case are therefore incorrect. Accordingly,
and as described more fully below, we reverse and remand
for further proceedings.
                       BACKGROUND
                A. The TT Patent Family
    TT owns a number of related patents generally di-
rected to software used for electronic trading on a com-
modities exchange, including the ’411, ’768, ’374, and ’055
patents at issue in this appeal. Issued between March
2010 and March 2011, those four patents claim priority


    *  Honorable Dee V. Benson, District Judge, United
States District Court for the District of Utah, sitting by
designation.
TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC            5
from U.S. Provisional Patent Application 60/186,322, filed
on March 2, 2000, and U.S. Patent Application
09/590,692, which was filed on June 9, 2000, and later
issued as U.S. Patent 6,772,132 (the “’132 patent”) on
August 3, 2004. The ’411, ’768, and ’374 patents all arose
from a series of continuation applications stemming from
the parent ’132 patent. See, e.g., ’411 patent, at [63].
Accordingly, the ’411, ’768, and ’374 patents share a
common written description matching that of the progeni-
tor ’132 patent in all material respects. In contrast, the
’055 patent traces its priority from the ’132 patent as a
continuation-in-part, see ’055 patent, at [63], and as such,
the ’055 patent contains substantial new matter relative
to the original written description of the ’132 patent.
    In general, the subject TT patents concern a graphical
user interface that can display essential data from a
commodities market and allow a user to enter electronic
trade orders on an exchange. Drawings common to the
’411, ’768, ’374, and ’055 patents exemplify several key
aspects of the disclosed displays:
6             TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC
E.g., ’411 patent, figs. 3, 4. Figure 3 depicts a trading
display that conveys up-to-date market information,
including the pending bids and offers at various price
points. Column 1005, labeled “Prc,” represents various
contract prices for the commodity of interest. Id. col. 7
ll. 55–58. Adjacent to the price column are bid and ask
columns 1003 and 1004, labeled “BidQ” and “AskQ,”
respectively. Those columns show the current bid quanti-
ties (offers to buy) and ask quantities (offers to sell) at
each price, id. col. 7 ll. 54–55, and a trader can enter new
trade orders by clicking on the bid and ask columns, id.
col. 10 ll. 19–23. The “inside market,” labeled 1020, spans
the highest current bid price and the lowest current ask
price. Id. col. 4 ll. 60–62. In general, the inside market
approximates the commodity’s market price and therefore
marks a focus of trading activity. In figure 3, the inside
market includes a highest bid price of 89 and a lowest ask
price of 90.
     Figure 4 shows the same display, with data for the
same market, viewed at a later point in time. ’411 patent
col. 3 ll. 47–48. Over time, the inside market can “ascend
and descend as prices in the market increase and de-
crease.” Id. col. 9 ll. 4–5. As illustration, the inside
market in figure 4, labeled 1101, has shifted up the price
column to 92/93 from its earlier range of 89/90 in response
to intervening trades.
    According to the patents, traders able to view and
quickly appreciate such detailed market data can more
readily identify (and capitalize upon) developing trends in
an active market. Id. col. 6 ll. 12–30. To that end, the
disclosed graphical user interfaces offer a logical and
intuitive means to convey dynamic market information
using bid, ask, and inside market indicators that visually
track ongoing price fluctuations along the price column.
Moreover, the patents combine a market grid, a summary
of market orders, and an order entry system into a single
display. In short, “[s]uch a condensed display materially
TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC            7
simplifies the trading system by entering and tracking
trades in an extremely efficient manner.” Id. col. 7 ll. 40–
42.
    Nonetheless, allowing the inside market to move up
and down the display presents a problem: “As the market
ascends or descends the price column, the inside market
might go above or below the price column displayed on a
trader’s screen.” Id. col. 9 ll. 15–17. Because the inside
market informs most trading decisions, the display must
provide a way to re-center the price column and bring the
inside market back into view. The parent ’132 written
description shared by the ’411, ’768, and ’374 patents
explains that the values in the price column “are static;
that is, they do not normally change positions unless a re-
centering command is received,” id. col. 7 ll. 64–66, and
further describes a “one click” centering feature that
allows a user to re-center the price column around the
inside market with a single mouse click, id. col. 9 ll. 17–
25.
                 B. The eSpeed Decision
    As noted, this appeal is not the first to reach this
court concerning TT’s trading software patents.          In
eSpeed, we considered, inter alia, the correct construction
of certain claim terms used in the ’132 patent and in
another of its many descendants, U.S. Patent 6,766,304
(the “’304 patent”). The ’304 patent, like the ’411, ’768,
and ’374 patents, shares the written description of the
parent ’132 patent.1
    In eSpeed, TT had asserted claims from the ’132 and
’304 patents against several providers of electronic trad-
ing software. 595 F.3d at 1347–48. Each of the asserted


   1    The ’304 patent issued from a division of the
application underlying the ’132 patent. ’304 patent, at
[62].
8             TRADING TECHNOLOGIES INTL    v. OPEN E CRY, LLC
claims required a graphical user interface having a “stat-
ic” display of market price information,2 and the district
court had construed that term to require “a display of
prices comprising price levels that do not change positions
unless a manual re-centering command is received.” Id.
at 1352. On appeal, TT argued that a “static” price col-
umn could work with non-manual modes of re-centering.
Id. at 1353.
     Relying on the ’132 and ’304 patents’ shared written
description, the surrounding claim language, and the
relevant prosecution history, we adopted the district
court’s construction. See id. at 1353–55. In particular, we
concluded that “[t]he inventors’ own specification strongly
suggests that the claimed re-centering feature is manual”
because the written description “only discusse[d] manual
re-centering commands” and referred to “the present
invention” as including a manual one-click re-centering
feature. Id. at 1353–54. Consistent with that view, we
also noted that the claims of the ’132 patent recited an
additional limitation stating that the “static” price display
would not move in response to changes in the inside
market, expressly excluding displays that re-center auto-
matically when the inside market shifts. Id. at 1354.
Finally, we highlighted statements made by the appli-
cants during prosecution. Specifically, the examiner had
first considered the term “static display” to be indefinite,
but the applicants responded by explaining that the
values in the price column would not change absent a re-

    2    The asserted claims of the ’132 patent required a
“static display of prices,” while the asserted claims of the
’304 patent required a “common static price axis.” The
eSpeed claim construction debate nonetheless turned on
the meaning of “static” because all agreed that “the
difference in terminology between ‘static display of prices’
and ‘common static price axis’ [was] immaterial.” eSpeed,
595 F.3d at 1352.
TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC              9
centering command, and the claims were then allowed on
that basis. Id. at 1354. Accordingly, the full record before
us in eSpeed led us to conclude that the proper construc-
tion of “static,” as used in the claims of the ’132 and ’304
patents, required a price column that moves only in
response to a manual re-centering command.
    In addition, we rejected TT’s attempts to invoke the
doctrine of equivalents to find that products practicing
automatic re-centering nonetheless infringed its claims to
“static” displays. See id. at 1355–57. We held that prose-
cution history estoppel precluded such infringement
theories because the applicants had amended the claims
of the ’132 and ’304 patents to make clear that the
claimed “static” price levels did not move in response to
changes in the inside market, thus “surrender[ing] any
subject matter that moves automatically.” Id. at 1357.
Thus, in eSpeed, “both claim construction and prosecution
history estoppel operate[d] . . . with similar limited re-
sults.” Id.
 C. Prosecution of the ’411, ’768, ’374, and ’055 Patents
    While the eSpeed litigation progressed through the
courts, four patent applications that eventually became
the ’411, ’768, ’374, and ’055 patents were filed in the
United States Patent and Trademark Office. TT followed
two distinct approaches to prosecuting those applications
in view of eSpeed. Those approaches are key to the reso-
lution of this appeal.
        1. The ’411, ’768, and ’374 Continuations
    With the applications for the ’411, ’768, and ’374 pa-
tents—three parallel continuations that relied on the
original written description of the ’132 patent—TT sought
claims that removed the term “static” from references to
the price column. For example, following the district
court’s adverse claim construction determinations in the
10            TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC
eSpeed litigation,3 TT amended the application for the
’411 patent. Up to that time, the application had claimed
methods requiring “statically” displayed market price
information, similar to the claims of the related ’132 and
’304 patents at issue in eSpeed. But TT’s amendment
cancelled every pending claim and introduced new claims
that lacked the term “static” in any form, and that term
remained absent from the claims issued in the ’411 pa-
tent. In addition, TT made comparable amendments to
the co-pending applications that gave rise to the ’768 and
’374 patents.
    Therefore, while the written descriptions of the ’411,
’768, and ’374 patents match those of the earlier ’132 and
’304 patents, the claims differ between the two groups in
at least one key respect—unlike the ’132 and ’304 patents
at issue in eSpeed, the ’411, ’768, and ’374 patents claim
trading methods and software without limitation to a
“static” price column display.
            2. The ’055 Continuation-in-Part
    TT pursued a different strategy with the application
for the ’055 patent. That application claimed priority
from the ’132 patent as a continuation-in-part, which
allowed TT to add new disclosures to the parent’s written
description. In part, those additional disclosures were
aimed at redefining the term “static” as used in the ’055
patent:



     3  In that case, the district court issued an initial
claim construction ruling on October 31, 2006, and then
issued another order clarifying its original construction on
February 21, 2007. Trading Techs. Int’l, Inc. v. eSpeed,
Inc., Nos. 04-c-5312, 05-c-1079, 05-c-4088, 05-c-4120, 05-c-
4811, 05-c-5164, 2006 WL 3147697 (N.D. Ill. Oct. 31,
2006), clarified, 2007 WL 611258 (N.D. Ill. Feb. 21, 2007).
TRADING TECHNOLOGIES INTL    v. OPEN E CRY, LLC                11
    Certain of the trading tools work particularly well
    with a trading display that shows working orders .
    . . displayed in association with a static price scale
    or axis. . . . It is to be understood that, in this con-
    text, static does not mean immovable, but rather
    means fixed in relation. For example, with a stat-
    ic price scale, the scale itself may be movable, but
    the prices represented remain fixed in relation to
    each other . . . .
’055 patent col. 4 ll. 48–57 (emphases added); see also id.
col. 25 ll. 4–12 (“In one embodiment, the trading applica-
tion tracks the market’s activity by automatically center-
ing, for example, the inside market . . . on the display
with respect to a static axis or scale of prices.”); id. col. 26
ll. 30–37 (“A trader may use automatic positioning to
always have a visual reference of where the market is
trading . . . . In addition, automatic positioning may be
used in conjunction with manual positioning.”).
    The claims of the ’055 patent likewise recite steps that
include displaying “a static price axis” and “automatically
repositioning the static price axis on the graphical user
interface.” Id. col. 34 ll. 15–67. By their terms, the claims
of the ’055 patent thus require a “static price axis” capable
of re-centering via automatic rather than manual com-
mands.
               D. District Court Proceedings
    In early 2010, TT filed twelve separate infringement
actions targeting numerous defendants, including: Open
E Cry, LLC; optionsXpress Holdings, Inc.; TradeStation
Securities, Inc.; TradeStation Group, Inc.; IBG, LLC;
thinkorswim Group, Inc.; TD Ameritrade, Inc.; TD Ameri-
trade Holding Corp.; Interactive Brokers, LLC; CQG, Inc.;
CQGT, LLC; FuturePath Trading, LLC; SunGard Data
Systems, Inc.; SunGard Investment Ventures LLC; GL
Trade Americas, Inc.; Stellar Trading Systems, Ltd.;
Stellar Trading Systems, Inc.; eSpeed Markets, LP; BGC
12            TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC
Capital Markets, LP; Eccoware, Ltd.; and Rosenthal
Collins Group, LLC (collectively, “Defendants”).4 Through
a series of supplements and amendments to the original
complaints, TT variously accused the Defendants of
infringing claims from more than ten patents relating to
electronic trading software, of which only the ’411, ’768,
’374, and ’055 patents are before us in this appeal. The
district court consolidated the cases on February 3, 2011.
Trading Techs. Int’l, Inc. v. BGC Partners, Inc., No. 10-cv-
715 (N.D. Ill. Feb. 3, 2011), ECF No. 70 (Consolidation
Order).
    After consolidation, the parties submitted opposing
summary judgment motions on several issues, including
whether the claims of the ’411 patent satisfied the written
description requirement of 35 U.S.C. § 112(a) in light of
eSpeed and whether prosecution history estoppel barred
TT from asserting infringement under the doctrine of
equivalents as to products with price columns that move
automatically. Trading Techs. Int’l, Inc. v. BCG Partners,
Inc., 852 F. Supp. 2d 1027, 1029–30 (N.D. Ill. 2012)
(“Summary Judgment Order”).
    First, the district court concluded that eSpeed re-
quired holding the claims of the ’411 patent invalid for
lack of written description. The court acknowledged that
eSpeed did not involve the ’411 patent or the written
description requirement and instead dealt primarily with
construing the term “static” in the claims of the ’132 and
’304 patents. Id. at 1044. Nevertheless, the district court
reasoned that eSpeed “made a number of findings regard-
ing the specification in the course of affirming the claim
construction that are dispositive here.” Id.



     4  Although a defendant before the district court,
Rosenthal Collins Group, LLC is not a party to this
appeal.
TRADING TECHNOLOGIES INTL    v. OPEN E CRY, LLC            13
    According to the district court, eSpeed’s construction
of “static” in the ’132 and ’304 patents turned “on the
premise that the invention described in the specification
was limited to static price axes that move only with
manual re-centering.” Id. at 1045. Because the ’411
patent’s claims lacked that term and therefore appeared
to cover displays with automatic re-centering, the district
court concluded that any decision upholding those broader
claims as supported by the same written description
“would be at odds with the Federal Circuit’s binding
findings in the eSpeed Decision.” Id. In granting the
Defendants’ motion for summary judgment, the district
court expressly declined to evaluate the parties’ evidence
or make its own findings on the merits because the court
determined “as a matter of law that the eSpeed Decision
controls.” Id. at 1038 n.9; see also id. at 1045 n.13.
    In addition, the district court held that eSpeed’s appli-
cation of prosecution history estoppel to the ’132 and ’304
patents applied equally to the ’055 patent as a matter of
law.5 The court noted that the ’055 patent’s claims “in-
clude the limitation of ‘common static price axis,’ just like
the ’304 patent, and flow from . . . a similar specification.”
Summary Judgment Order, 852 F. Supp. 2d at 1046–47.
The court then concluded that when “‘multiple patents
derive from the same initial application, the prosecution
history regarding a claim limitation in any patent that
has issued applies with equal force to subsequently issued
patents that contain the same claim limitation.’” Id. at
1046 (quoting Elkay Mfg. Co. v. Ebco Mfg. Co., 192 F.3d
973, 980 (Fed. Cir. 1999)). TT argued that prosecution
disclaimers affecting the ’132 and ’304 patents should not
automatically limit the ’055 patent, with its distinct and

    5   In addition to the ’055 patent, the district court
applied prosecution history estoppel to two other related
TT patents, but those patents are not included in this
appeal.
14            TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC
contravening additional disclosures, but the district court
disagreed. “That the ’055 patent is only a continuation-in-
part makes no difference.” Id. at 1047 n.15. The district
court therefore held that TT was estopped from asserting
that any claims of the ’055 patent were infringed under
the doctrine of equivalents by a product with a price axis
that moves automatically. Id. at 1048.
    Following the Summary Judgment Order, the district
court held a status hearing and ordered the parties to file
a joint response summarizing the effects of its ruling on
each patent in suit. The parties agreed that the decision
had rendered the following claims invalid: all claims of
the ’411 patent except claim 15, all claims of the ’768
patent, and all claims of the ’374 patent except claims 7
and 11. The parties disagreed, however, on the status of
the ’055 patent. The Defendants contended that, in view
of eSpeed, the ’055 patent claims remained valid but
limited in scope. TT maintained that the ’055 patent’s
added disclosures ascribed a different meaning to “static”
in that patent relative to those at issue in eSpeed. There-
fore, TT asserted, the district court’s Summary Judgment
Order, which relied on eSpeed, should not affect the ’055
patent for purposes of prosecution history estoppel or
otherwise.
     The district court issued a subsequent order denying
TT’s motion to reconsider the prosecution history estoppel
ruling, extending its invalidity holding, and certifying
partial judgment for immediate appeal. Trading Techs.
Int’l, Inc. v. BCG Partners, Inc., 883 F. Supp. 2d 772 (N.D.
Ill. 2012) (“Certification Order”). Specifically, the court
reaffirmed its conclusion that prosecution history estoppel
applied to the ’055 patent because of eSpeed despite the
’055 patent’s distinct disclosures and prosecution history
as a continuation-in-part. Id. at 778–79. And having
concluded that eSpeed applied to the ’055 patent, the
court decided that its Summary Judgment Order ren-
dered the ’055 patent invalid. Certification Order, 883 F.
TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC           15
Supp. 2d at 781 n.1. The district court also agreed with
both parties that its earlier order had largely invalidated
the ’768 and ’374 patents as well. Id. at 782–84. Finally,
the court found no just reason to delay an appeal as to
those issues and therefore entered partial final judgment
pursuant to Federal Rule of Civil Procedure 54(b).6
    TT filed a timely appeal, and we have jurisdiction un-
der 28 U.S.C. § 1295(a)(1).
                       DISCUSSION
    Summary judgment is appropriate “if the movant
shows that there is no genuine dispute as to any material
fact and the movant is entitled to judgment as a matter of
law.” Fed. R. Civ. P. 56(a). We apply the law of the
regional circuit when reviewing a district court’s entry of
summary judgment. Teva Pharm. Indus., Ltd. v. Astra-
Zeneca Pharm. LP, 661 F.3d 1378, 1381 (Fed. Cir. 2011).
The Seventh Circuit reviews the grant or denial of sum-
mary judgment without deference. Omnicare, Inc. v.
UnitedHealth Grp., Inc., 629 F.3d 697, 723 (7th Cir.
2011). “Compliance with the written description re-
quirement is a question of fact but is amenable to sum-
mary judgment in cases where no reasonable fact finder
could return a verdict for the non-moving party.”
PowerOasis, Inc. v. T-Mobile USA, Inc., 522 F.3d 1299,
1307 (Fed. Cir. 2008). Prosecution history estoppel oper-
ates as a legal limitation on a patentee’s ability to invoke

   6    The court noted that TT had agreed “to enter into
a covenant not to sue on any of the remaining valid
claims of the ’411, ’768, ’374, and ’055 patents.”
Certification Order, 883 F. Supp. 2d at 782 (emphasis
added). We interpret the district court’s statements to
mean that its final judgment invalidated the following
claims: claims 1–14 and 16–28 of the ’411 patent; all
claims of the ’768 patent; claims 1–6, 8–10, and 12–36 of
the ’374 patent; and all claims of the ’055 patent.
16            TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC
the doctrine of equivalents, and we review its application
de novo. eSpeed, 595 F.3d at 1355.
                 A. Written Description
    As described, the district court granted summary
judgment in favor of the Defendants as to the invalidity of
most claims of TT’s ’411, ’768, ’374, and ’055 patents,
holding that our prior decision in eSpeed rendered those
claims invalid as a matter of law for failing to satisfy the
written description requirement of § 112.
     TT argues that the district court relied on portions of
eSpeed that dealt solely with interpreting the term “stat-
ic” in the related ’132 and ’304 patents without determin-
ing or addressing the scope of the patents’ shared
disclosure. Noting that the sufficiency of a patent’s writ-
ten description presents a question of fact, TT faults the
district court for relying entirely on eSpeed rather than
conducting its own analysis of whether any of the claims
at issue find adequate written description support under
§ 112. TT contends that, on the merits and apart from
any misapplication of eSpeed, the claims of the ’411, ’768,
’374, and ’055 patents satisfy the written description
requirement.
    The Defendants respond that the district court
properly relied on eSpeed because eSpeed’s claim con-
struction analysis turned on the same basic issue as the
present written description inquiry—whether the original
’132 patent discloses a display with a price column that
moves through means other than manual re-centering.
According to the Defendants, that issue was finally and
necessarily decided in eSpeed, precluding any contrary
findings in this case.
    As explained more fully below, we conclude that the
district court placed undue reliance on eSpeed in its
written description analysis and thus erred when it held
TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC            17
TT’s claims invalid without considering the scope of the
claims in light of the underlying disclosures.
            1. The ’411, ’768, and ’374 Patents
    The ’411, ’768, and ’374 patents all rely on the same
underlying disclosure as the ’132 and ’304 patents dis-
cussed in eSpeed. But the claims of the patents now
before us are different, as are the issues at play, and
eSpeed’s ruling on claim construction does not govern the
written description inquiry in this case.
     The question here is whether the patents’ common
disclosure provides adequate support for claims not
limited to displays with “static” price axes, i.e., claims
broad enough to encompass some form of automatic re-
centering. In explaining its reliance on eSpeed, the dis-
trict court correctly perceived that the written description
and claim construction analyses both look to a patent’s
specification for guidance.      See Summary Judgment
Order, 852 F. Supp. 2d at 1045 (stating that “§ 112 ques-
tions and claim construction questions look to the specifi-
cation first and foremost”). Despite their similarities,
however, claim construction and the written description
requirement are separate issues that serve distinct pur-
poses.
    In construing claims, a court seeks to discern the
meaning of a particular term used in one or more claims
of a patent, based, inter alia, on evidence drawn from the
specification, the surrounding claim language, the prose-
cution history, and relevant extrinsic sources. See gener-
ally Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005)
(en banc). The specification is fundamental to claim
construction, as “‘it is the single best guide to the meaning
of a disputed term.’” Id. at 1315 (quoting Vitronics Corp.
v. Conceptronic, Inc., 90 F.3d 1576, 1582 (Fed. Cir. 1996)).
While guided by the specification, the focus of claim
construction remains on defining a discrete claim term to
better ascertain the boundaries of a claim. In contrast,
18            TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC
the written description analysis considers the bounds of
the specification itself. The written description require-
ment prevents patentees from claiming more than they
have actually invented and disclosed to the public, as
measured by the written description of the invention
provided with their patent applications. In other words,
the written description requirement “ensure[s] that the
scope of the right to exclude, as set forth in the claims,
does not overreach the scope of the inventor’s . . . patent
specification.” Reiffin v. Microsoft Corp., 214 F.3d 1342,
1345 (Fed. Cir. 2000).
     This case illustrates the distinction. In eSpeed, we
were called upon to evaluate the proper construction of
“static,” a term used in the claims of the ’132 and ’304
patents. Accordingly, we considered the evidence relevant
to a proper reading of that term, starting with those
patents’ common written description. eSpeed, 595 F.3d at
1353–55. Noting that the patents referred to one-click
centering as part of the invention and did not discuss
automatic re-centering, we concluded that the specifica-
tion “strongly suggests” that a “static” price column would
require manual re-centering. Id. at 1353–54. And even
though the patents described price columns that “do not
normally change positions unless a re-centering command
is received,” ’132 patent col. 7 ll. 46–48 (emphasis added),
we concluded that “the inventors jettisoned the word
‘normally’ during prosecution” by limiting the term “stat-
ic” in response to an indefiniteness rejection, eSpeed, 595
F.3d at 1354. In sum, we concluded that the disputed
claim term should be limited to require a manual re-
centering command in the claims of the ’132 and ’304
patents.
    But our decision in eSpeed did not thereby determine
whether the same written description would also support
different claims drawn to a non-“static” display. In par-
ticular, we did not make “findings regarding the specifica-
tion . . . that are dispositive” as to the present written
TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC            19
description challenge. See Summary Judgment Order,
852 F. Supp. 2d at 1044. On the contrary, we merely
determined the best construction for a single disputed
claim term, a term that is absent from the claims of the
’411, ’768, and ’374 patents now before us. That analysis
did not require us to pass on the outer limits of the pa-
tents’ written description, nor did we endeavor to do so.
In fact, our prior examination of that written description
did not even settle the limited claim construction issue
then facing the court, see eSpeed, 595 F.3d at 1353–54
(concluding that the specification “strongly suggests” that
the claimed re-centering feature is manual), much less
conclusively find that the same written description could
never support any claim to a display with a non-“static”
price axis.
    To be clear, we express no opinion as to whether or
not the claims of the ’411, ’768, and ’374 patents now
before us satisfy the written description requirement. We
leave that determination for the district court to make in
the first instance based on its own review of the disclo-
sures underlying those particular claims. We hold only
that eSpeed did not settle the issue, and we therefore
reverse the district court’s entry of summary judgment of
invalidity and remand for further proceedings on the
merits under § 112.
                    2. The ’055 Patent
    The district court devoted scant analysis to the validi-
ty of the ’055 patent’s claims, noting summarily that its
judgment regarding the ’411 patent had also invalidated
the ’055 patent. Certification Order, 883 F. Supp. 2d at
782 n.1. For the reasons already set forth, that holding
was unsound as far as it relied on eSpeed as dispositive of
validity under the written description requirement in this
case. But the district court’s invalidity ruling suffers from
additional problems specific to the ’055 patent.
20              TRADING TECHNOLOGIES INTL    v. OPEN E CRY, LLC
    In contrast to the ’411, ’768, and ’374 patents, the ’055
patent was filed as a continuation-in-part application,
which allowed TT to disclose and claim additional subject
matter in the ’055 patent. PowerOasis, 522 F.3d at 1304
n.3 (“[A] continuation-in-part application contain[s] a
portion or all of the disclosure of an earlier application
together with added matter not present in that earlier
application. . . . Generally, a CIP adds new matter on
which at least one claim relies for support.”); 37 C.F.R.
§ 1.53(b)(2) (“A continuation-in-part application . . . may
disclose and claim subject matter not disclosed in the
prior application . . . .”).
    As such, the ’055 patent differs fundamentally from
those at issue in eSpeed, and its unique written descrip-
tion was never considered in that case. Furthermore, the
supplemental disclosures in the ’055 patent are exten-
sive—the ’055 patent’s written description spans thirty-
four printed columns, compared to just eleven in the ’132
patent—and directly relevant to the written description
question presented here. For example, the new matter
added to the ’055 patent includes express descriptions of
“static” price axes that can automatically re-center based
on predefined criteria:
     In one embodiment, the trading application tracks
     the market’s activity by automatically centering,
     for example, the inside market . . . on the display
     with respect to a static axis or scale of prices. . . .
     ....
     . . . When . . . the inside market line is outside of
     the viewable area of a trader’s display, or is more
     than a predetermined distance away from a loca-
     tion on the display, the . . . inside market line will
     automatically be placed at a predetermined loca-
     tion on the display.
TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC            21
’055 patent col. 25 ll. 6–38. In turn, those new disclosures
correspond directly to accompanying claim limitations
recited in the ’055 patent. See id. col. 34 ll. 60–67 (“auto-
matically repositioning the static price axis on the graph-
ical user interface such that a current inside market price
is displayed at a new desired location”).
    Given such unambiguous support for claims requiring
“automatic[] repositioning the static price axis,” it cannot
be said that the ’055 patent’s written description does not
“reasonably convey[] to those skilled in the art that the
inventor had possession of the claimed subject matter as
of the filing date” of the ’055 patent. Ariad Pharm., Inc. v.
Eli Lilly & Co., 598 F.3d 1336, 1351 (Fed. Cir. 2010) (en
banc). We therefore conclude that TT is entitled to sum-
mary judgment that the claims of the ’055 patent have not
been proven invalid by clear and convincing evidence for
lack of adequate written description. Accordingly, we
reverse the district court’s summary judgment of invalidi-
ty and its denial of TT’s cross-motion regarding the claims
of the ’055 patent.
             B. Prosecution History Estoppel
    Finally, before holding the claims of the ’055 patent
invalid under § 112, the district court also held that “TT is
estopped from asserting that any [claims of the ’055
patent] can be infringed under the doctrine of equivalents
by a product that has a price axis that moves automatical-
ly or re-centers automatically.” Summary Judgment
Order, 852 F. Supp. 2d at 1048. According to the district
court, prosecution history estoppel imposed against the
’132 and ’304 patents in eSpeed also extended to the later
’055 patent. Id. at 1046.
    TT maintains that the new matter added to the ’055
patent plainly establishes that the claim term “static” has
a broader meaning in the ’055 patent than in the ’132 and
’304 patents. In addition, TT asserts that the district
court committed legal error by holding that prosecution
22            TRADING TECHNOLOGIES INTL    v. OPEN E CRY, LLC
history estoppel regarding that term in the ’132 and ’304
patents necessarily applies to all of their progeny, includ-
ing the continuation-in-part ’055 patent.
    The Defendants answer that eSpeed included a bind-
ing legal determination regarding the prosecution history
of the “static” claim limitation in the TT patent family,
which applies equally to the ’055 patent’s use of that term
in the same context and in a similar specification. Fur-
thermore, the Defendants suggest that even if TT could
rescind its earlier disclaimer, the ’055 patent contains
only vague or ambiguous statements that do not suffice to
broaden the scope of “static price axis” beyond that estab-
lished in eSpeed.
    As an initial matter, although the parties have la-
beled their disagreement as one pertaining to prosecution
history estoppel, we note some ambiguity as to whether
the substance of their arguments and the district court’s
ruling in fact concerns prosecution history estoppel,
prosecution disclaimer, or both.      Prosecution history
estoppel applies as part of an infringement analysis to
prevent a patentee from using the doctrine of equivalents
to recapture subject matter surrendered from the literal
scope of a claim during prosecution. Pall Corp. v. Hema-
sure Inc., 181 F.3d 1305, 1311 (Fed. Cir. 1999). Prosecu-
tion disclaimer, on the other hand, affects claim
construction and applies where an applicant’s actions
during prosecution prospectively narrow the literal scope
of an otherwise more expansive claim limitation. Omega
Eng’g, Inc. v. Raytek Corp., 334 F.3d 1314, 1323–24 (Fed.
Cir. 2003). Though distinct, both doctrines serve to
constrain the enforceable scope of patent claims commen-
surate with any subject matter surrendered during prose-
cution to obtain the patent, and a single action during
prosecution can engender both a prosecution disclaimer
and prosecution history estoppel. See, e.g., Elkay, 192
F.3d at 978–79, 981; Spectrum Int’l, Inc. v. Sterilite Corp.,
164 F.3d 1372, 1380 (Fed. Cir. 1998).
TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC           23
    Here, as noted, the district court based its prosecution
history estoppel analysis on eSpeed. But eSpeed ad-
dressed prosecution history estoppel and prosecution
disclaimer, 595 F.3d at 1357 (noting that “both claim
construction and prosecution history estoppel operate in
this case with similar limited results”), and those parallel
discussions appear to have been conflated in this case.
    The district court found that an amendment inserting
the term “common static price axis” into the claims of the
’132 and ’304 patents had driven the prosecution history
estoppel ruling in eSpeed. Summary Judgment Order,
852 F. Supp. 2d at 1046 (“[T]he Federal Circuit found that
inserting the limitation of ‘common static price axis’ into
the claims of the ’304 patent prevented TT from asserting
that products with price axes that move automatically . . .
infringe under the doctrine of equivalents.”). Because the
’055 patent’s claims include essentially the same limita-
tion, the district court reasoned that the holding in eSpeed
must also apply to the ’055 patent. Id. at 1047 (“Where
the same claim term is at issue in the same context, TT’s
disclaimer as to the ’304 patent applies to the [’055 pa-
tent].”). But the amendments that gave rise to prosecu-
tion history estoppel in eSpeed did not introduce a “static”
price axis into the claims—that term was already present.
They instead “clarified that the claimed price levels ‘do
not move’ when the inside market changes.” eSpeed, 595
F.3d at 1357.
    Thus, the term “static” (or “common static price axis”)
itself did not form the basis for our prosecution history
estoppel determination in eSpeed. Furthermore, the key
“do not move” language added by amendment to the ’132
and ’304 patents does not recur in the claims of the ’055
patent. Alternatively, the issue of prosecution disclaimer
in eSpeed did turn on discussion of the term “static”
during prosecution, id. at 1354–55, and, as noted, that
term does appear in the claims of the ’055 patent. In
addition, the district court’s opinion and the parties’
24            TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC
briefing before this court variously touch on claim con-
struction while ostensibly discussing prosecution history
estoppel. See, e.g., Summary Judgment Order, 852 F.
Supp. 2d at 1047 (summarizing relevant authorities as
“concerned about consistency of constructing claims”);
Appellant’s Br. 41 (“[T]he dispositive issue is whether the
term has the same meaning.”).
    Regardless, whether viewed through the lens of
prosecution history estoppel or prosecution disclaimer, the
basic question here is whether TT’s earlier prosecution-
based “surrender[] [of] any subject matter that moves
automatically,” eSpeed, 595 F.3d at 1357, carries through
from the ’132 and ’304 patents to limit the enforceable
scope of the ’055 continuation-in-part. We hold that it
does not.
    Prosecution history estoppel can extend from a parent
application to subsequent patents in the same lineage,
Elkay, 192 F.3d at 981, as can a prosecution disclaimer,
Omega Eng’g, 334 F.3d at 1333–34. But “arguments
made in a related application do not automatically apply
to different claims in a separate application.” Biogen, Inc.
v. Berlex Labs., Inc., 318 F.3d 1132, 1139 (Fed. Cir. 2003).
In general, the prosecution history regarding a particular
limitation in one patent is presumed to inform the later
use of that same limitation in related patents, “unless
otherwise compelled.” Omega Eng’g, 334 F.3d at 1334.
    In this case, the intrinsic record specific to the ’055
patent distinguishes eSpeed and compels a different
result. The ’055 patent, as a continuation-in-part of the
’132 patent, includes extensive disclosures that were not
present in the ’132 or ’304 patents, and those subsequent
disclosures directly contradict the prosecution-based
surrenders of claim scope discussed in eSpeed. For exam-
ple, the ’055 patent states that “static does not mean
immovable,” ’055 patent col. 4 l. 54, and describes “auto-
matically repositioning the static price axis upon detect-
TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC           25
ing a predetermined condition,” id. col. 3 ll. 19–20. Fur-
thermore, the claims of the ’055 patent lack the “do not
move” limitations that accompanied the term “static” in
the ’132 and ’304 patents. See eSpeed, 595 F.3d 1356–57.
Rather, the claims of the ’055 patent contain express
language requiring automatic movement of the static
price axis. ’055 patent col. 34 ll. 60–67. Finally, TT made
clear during prosecution of the ’055 patent—before the
same examiner who had handled the ’132 and ’304 pa-
tents—that the “static” price axis described and claimed
in the ’055 patent was not limited to manual re-centering.
     While it retains the “static price axis” claim language
of its predecessors, the ’055 patent thus differs from the
’132 and ’304 patents in both its claims and its relevant
supporting disclosures on the issue of automatic re-
centering.     Those differences render eSpeed’s earlier
prosecution-based restrictions inapplicable to the ’055
patent. See Middleton, Inc. v. Minn. Mining & Mfg. Co.,
311 F.3d 1384, 1389 (Fed. Cir. 2002). “When the purport-
ed disclaimers are directed to specific claim terms that
have been omitted or materially altered in subsequent
applications . . . those disclaimers do not apply.” Saun-
ders Grp., Inc. v. Comfortrac, Inc., 492 F.3d 1326, 1333
(Fed. Cir. 2007). Accordingly, the claims of the ’055
patent, unlike those of the related ’132 and ’304 patents,
need not be limited to displays with price axes capable
only of manual re-centering, whether by prosecution
disclaimer or prosecution history estoppel. The district
court’s decisions (i) granting summary judgment that
prosecution history estoppel applies to the ’055 patent,
and (ii) denying TT’s cross-motion, are reversed.
                       CONCLUSION
    As explained above, we conclude that eSpeed does not
govern the issues of written description or prosecution
history estoppel raised in this appeal. We reverse and
26          TRADING TECHNOLOGIES INTL   v. OPEN E CRY, LLC
remand for further proceedings consistent with this
opinion.
          REVERSED AND REMANDED
