concurring in the judgment of invalidity of the ‘313 patent.
I believe that U.S. Patent No. 4,081,313 (’313 patent), a continuation-in-part of U.S. Patent No. 3,623,712 (’712 patent), failed to disclose the best mode for practicing the claimed invention. Inventors must update their best mode disclosure when filing a continuation-in-part which adds new matter pertinent to the best mode of practicing the invention claimed in the continuation-in-part. The inventors here did not do so, and the ’313 patent is invalid.
In determining whether the ’313 patent is invalid because of a sale that predated the filing date by more than one year, 35 U.S.C. § 102(b) (1994), the district court found that the ’313 continuation-in-part application was enabled by the parent ’712 patent and was entitled to the filing date of that patent. Applied Materials Inc. v. Advanced Semiconductor Materials Am., Inc., 32 USPQ2d 1865, 1879-80, 1994 WL 362005 (N.D.Cal. 1994). The district court then held that the ’313 patent was invalid because the inventors added substantial new matter to the application but did not update the best mode for practicing the newly claimed invention. Id. at 1880-82.
Relying on Transco Products Inc. v. Performance Contracting, Inc., 38 F.3d 551, 32 USPQ2d 1077 (Fed.Cir.1994), Applied Materials argues here that the inventors were not obligated to update the best mode disclosure of the ’313 patent because it was enabled by the ’712 patent. This court adopts that position. But a continuation application, which was at issue in Transco, is fundamentally different from a continuation-in-part, which is at issue here.
To secure the benefit of the filing date of an earlier filed (“parent”) application, 35 U.S.C. § 120 requires that the claimed invention be disclosed in the manner provided by the first paragraph of section 112,1 which requires 1) a written description of the invention, 2) enablement, and 3) disclosure of the best mode for practicing the invention. Each of these disclosures is separately required before the later application is entitled to the filing date of the parent. See Transco, 38 F.3d at 556-57, 32 USPQ2d at 1081-82 (“[Sjection 120 speaks of the first paragraph of section 112 as a whole.” “Section 120 does not exempt the best mode requirement from its reach, and therefore this court must accept the plain and precise language of section 120 as encompassing the same.”).
Although there may be some variation in the scope of the claimed subject matter, a continuation application is based solely on the disclosure of a parent application. See Manual of Patent Examining Procedure § 201.07 (6th Ed.1995) (MPEP). By definition, a continuation adds no new matter and is akin to an amendment of a pending application. Id.; Cf. Godfrey v. Eames, 68 U.S. (1 Wall.) 317, 324-26, 17 L.Ed. 684 (1864). In addition to a continuation application, the *1580Patent and Trademark Office also permits a eontinuation-in-part application which is only partially entitled to the benefit of section 120 because it contains new matter. MPEP § 201.08. “A [continuation-in-part] application can be entitled to different priority dates for different claims. Claims containing any matter introduced in the [continuation-in-part] are accorded the filing date of the [eontinuation-in-part] application. However, matter disclosed in the parent application is entitled to the benefit of the filing date of the parent application.” Waldemar Link, GmbH & Co. v. Osteonics Corp., 32 F.3d 556, 558, 31 USPQ2d 1855, 1857 (Fed.Cir.1994).
Transco held that “an application is entitled to the benefit of the filing date of an earlier application as to common subject matter.” 38 F.3d at 557, 32 USPQ2d at 1082. Applied to the best mode requirement, this narrow statement means that an applicant is not required to update the best mode disclosure for continuation applications, which, of course, add no new matter, or for inventions claimed in continuation-in-part applications that are otherwise entitled to the filing date of a parent application because they meet all requirements necessary to gain the benefit of the earlier filing date. However, Transco’s general discussion of “continuing” applications should not be thought to apply the same requirements to both types of “continuing” applications without considering the important differences between them. Both continuations and eontinuations-in-part may be referred to as “continuing” applications for some purposes, but they are different in important respects.
The district court cited conflicting authority, Johns-Manville Corp. v. Guardian Indus. Corp., 586 F.Supp. 1034, 221 USPQ 319 (E.D.Mich.1983), affd, 770 F.2d 178 (Fed.Cir.1985), and Transco Products, Inc. v. Performance Contracting, Inc., 821 F.Supp. 537, 28 USPQ2d 1739 (N.D.Ill.1993), subsequently reversed, 38 F.3d 551, 32 USPQ2d 1077 (Fed.Cir.1994), from which it determined “that resolution of the best mode issue in the instant case requires an inquiry as to whether the Continuation In Part Application contained the disclosures of material essential to successfully practice the invention and which significantly amended the disclosure of the parent in a fashion known to the inventors to constitute best mode for the practice of the invention.” 32 USPQ2d at 1881. It found that the continuation-in-part that matured into the ’313 patent specifically claimed the benefits of a method of preparing crystallographic wafers with minimal crystallographic slip. Id. at 1881-82. The court also found that the inventors knew of a preferred embodiment for practicing the method of the ’313 patent before they filed their continuation-in-part application but failed to disclose it in the application.
The district court’s analysis is sound. Whereas the ’712 patent does not even contain the terms “slip” or “crystallographic slip,” the ’313 patent contains detailed information on how the claimed method heats a substrate formed of “a single crystal material with substantially no crystallographic slip.”2 It is beyond dispute that this information constitutes new matter and was at least one reason that the application was filed as a continuation-in-part, rather than a continuation. There is also no dispute over the factual findings that the inventors knew of a best mode of practicing the newly claimed invention and that they did not disclose it. The only argument is whether the district court’s finding that the ’313 patent was enabled by the ’712 patent is sufficient to absolve the inventors of any duty to update the best mode in their continuation-in-part application.
This court apparently overlooks that when the district court analyzed entitlement to the filing date of the parent it discussed only whether the ’313 patent claims were enabled by the parent application, not whether they met the best mode requirement. See 32 USPQ2d at 1879-80. Best mode is not the same as enablement. Chemcast Corp. v. *1581Arco Indus., 913 F.2d 923, 926, 16 USPQ2d 1033, 1035 (Fed.Cir.1990). Determining whether a patent complies with the best mode requirement involves two distinct factual inquiries that are different from what is required in determining whether the claimed invention is enabled. “First, it must be determined whether, at the time the patent application was filed, the inventor had a best mode of practicing the claimed invention.” U.S. Gypsum Co. v. National Gypsum Co., 74 F.3d 1209, 1212, 37 USPQ2d 1388, 1390 (Fed.Cir.1996). This “is wholly subjective and addresses whether the inventor must disclose any facts in addition to those sufficient for enablement.” Id. (emphasis added). “A specification can be enabling yet fail to disclose an applicant’s contemplated best mode.” Chemcast, 913 F.2d at 928, 16 USPQ2d at 1037. If the inventor contemplated a best mode of practicing the claimed invention, the court must then determine whether the specification adequately disclosed it so that those having ordinary skill in the art could practice it. Id. The district court performed this analysis without error.
The best mode requirement serves to “restrain inventors from applying for patents while at the same time concealing from the public preferred embodiments of their invention which they have in fact conceived.” Transco, 38 F.3d at 559, 32 USPQ2d at 1084 (citing In re Gay, 50 C.C.P.A. 725, 309 F.2d 769, 772, 135 USPQ 311, 315 (1962)). If an inventor may file a patent application disclosing only part of an invention, and then file a continuation-in-part adding substantial new matter without disclosing the best mode of what was newly added, the public will be deprived of the full invention claimed in the continuation-in-part application. It would behoove inventors to disclose only minimal parts of their inventions, and then submit continuations-in-part to claim the rest. They could thereby hide the commercial value that resides in the best mode of practicing their inventions and gain the benefit of both the exclusionary right of the patent and the “quasi trade secret” of the best mode.
This case highlights the need for inventors to update a best mode disclosure when adding new matter. Although the disclosure of the ’712 patent may have enabled one of ordinary skill in the art to practice the claimed process “with substantially no crystallographic slip,” only the ’313 continuation-in-part disclosed the advantages of the slip free process and specifically claimed it as the invention. In the interval, the inventors had developed a reactor that would optimize the advantages of this feature. To allow them to take advantage of the 1969 filing date almost 7 years later, add new matter to their application, and not require them to disclose the best mode of the newly claimed invention is a gross distortion of the bargain between the inventor and the public. See Bonito Boats Inc. v. Thunder Craft Boats, Inc., 489 U.S. 141, 150-51, 109 S.Ct. 971, 977-78, 103 L.Ed.2d 118, 9 USPQ2d 1847, 1852 (1989).
. Provided other requirements not at issue here are met, "[a]n application for patent for an invention disclosed in the manner provided by the first paragraph of [35 U.S.C. § 112] in an application previously filed in the United States ... shall have the same effect, as to such invention, as though filed on the date of the prior application.” 35 U.S.C. § 120 (1994).
. The most specific newly added references to the absence of crystallographic slip and to single crystal films occur in the '313 patent at column 1, lines 35-40 and 53-55; column 2, lines 38-45 and 55-61; column 3, lines 5-9 and 13-16; column 4 lines 3-5 and 24-27; column 5, lines 16-20; column 6, lines 5-7; column 10, lines 38-46; and column 11, line 19, through column 12, line 16.