The effects of In re Nuijten are still being felt today. Most recently, David Kappos released guidelines that “computer-readable medium” should now include the buzzword “non-transitory” so as to not include signals. The reasoning is that computer readable medium, when most broadly interpretated, could include a signal. The Federal Circuit in Nuijten rejected the signal claim for not fitting into any of the four categories because the signal is transient and not tangible. The court did acknowledge, however, that the signal is physical and man-made, exists in the real world, has tangible causes and effects, comprises particles, and is perceptible. However, “non-transitory” is an improper limitation for the PTO to mandate. Without a more expansive view of patentability, limitations to non-transitory media will continue to harm incentives for software development and escalate piracy.
Rather than disqualifying all transitory inventions, which goes against patent law precedent, a better approach is to focus on whether the invention is physical, transferable, and reproducible.
Historically, courts have allowed signals that have demonstrated physical qualities. The Supreme Court in Dolbear v. American Bell Tel. Co. held that electricity could be patentable subject matter. The Court reasoned that Bell’s art consisted in controlling the force as to make it accomplish its purpose. Such a purpose involved real, physical effects.
The Federal Circuit in Arrhythmia Research Technology, Inc. v. Corazonix Corp., while not dealing with signals as an article of manufacture, stated that “[t]he view that ‘there is nothing necessarily physical about ‘signals’’ is incorrect.” Importantly, other signal inventions have also been patented.
The USPTO, notably, has previously held an expansive view of allowing computer readable media other than non-transitory computer disks. In 1996, the idea of a propagated signal claim was widely unknown and under-appreciated in the software realm. However, after releasing the Computer-Related Invention Guidelines (“Guidelines”), the PTO also released Claim Examples to train examiners how to properly apply the Guidelines. These examples included a section on Compression and Encryption inventions. Claim 13, entitled Automated Manufacturing Plant, set forth the use of a signal claim.
A computer data signal embodied in a carrier wave comprising:
a. a compression source code segment comprising . . . [recites self-documenting source code]; and
b. an encryption source code segment comprising . . . [recites self-documenting source code].
In this example, the PTO instructions explained that the “computer data signal” was “specific software embodied on a computer-readable medium” and a “specific machine or manufacture.” This computer data signal controlled physical processes of the automated manufacturing plant. The current patent law should also reflect a standard of allowing as a patent-eligible article of manufacture physical inventions.
The Federal Circuit has held that signals that have physical effects are physical. Continuing to approve of physical signals as patent-eligible would not disrupt patent law.
Likewise, being able to transfer the physical embodiment of an invention sheds light on why the invention is patent-eligible as an article of manufacture. An article of manufacture software claim should be allowable when it represents a physical and transferable embodiment. When software is embodied on a physical medium, the intangible and non-rivalrous idea takes on a physical and rivalrous expression. Even as the transfer of transitory media (i.e. CDs, hard drives, USB drives, etc.) involves physical and rivalrous forms of transfers, so also does a signal involve a physical and rivalrous transfer. Like a CD, where a physical media that contains computer instructions can be transferred to only one person, using a transitory signal medium is similar. Each transfer of the software using a signal involves one medium on which the software resides. The software on such a medium is transferred to one recipient.
Methods are intangible and non-rivalrous forms of property. Software as an idea of a structure, relationship, or set of instructions that a computer can perform mimics the intangible and non-rivalrous elements of methods. However, when software is embodied in a physical medium, it meets the standard of a patent-eligible article of manufacture because a particular embodiment can be transferred.
Finally, not everything that has physical effects and transferable should meet the standard of patent-eligibility. The invention must be reproducible so that the invention as a whole is constant and predictable. Because file transfers normally follow protocols that do not permit errors, most signals that are used to transfer software should be patent-eligible. By adopting the standard of physical, transferable and reproducible, rather than non-transitory, a fair line for the patentability of signal claims is drawn, while at the same time encouraging growth in the very expanding area of software development.
Requiring software to be consistently (reproducible) measurable and transferrable (physical) makes software a manufacture fitting the invention into one of the four categories in § 101. Equally important, those characteristics embody the invention with a real-world application, clearing the abstract idea exception to non-patentability. The PTO is already rejecting claims that do not explicitly claim signal, but could be construed as including a signal. By restricting all signals as non-statutory subject matter, the patent system risks rejecting many futuristic inventions that are or could be construed as a signal.
Software must be embodied in a particular medium to avoid being interpreted as an abstract idea. Even when it is claimed on a physical medium, it still runs the risk of being interpreted as an abstract idea because the novelty of the invention is not the medium it is on. As § 101 was written in a time of physical and tangible articles, courts over the decades have appreciated the tangibility as being part of the invention. The medium is necessary to embody the invention as a non-abstract idea. It makes the invention reproducible, fixed, and constant.
In Benson, the first Supreme Court decision striking down a computer related invention for subject matter reasons, the Court stated that “one may not patent an idea.” The claim at issue dealt with the “processing of data by program and more particularly to the programmed conversion of numerical information” in general-purpose digital computers. Claimed as a method, this case differs from physical embodiments of software as an article that can be transferred and reproduced. Physical, reproducible signals should be patentable because of the way that it clears the abstract idea exception. Since software is patent-eligible based on its history of being patented, and because it does not fall within any exception to patentable subject matter, and as current characterizations of software are either not compelling enough to be allowed for subject matter, or too limiting to be easily infringed, a new perspective on understanding how software fits into the patent framework.
A recent example makes clear the important role the signal can play and the sense of including it. In Microsoft Corp. v. AT&T Corp., the Court stated in dicta that “[a]bstract software code is an idea without physical embodiment . . . .” The Court reasoned that in order for software to be a component, for purposes of § 271(f) it needed to be physically embodied. The Court further reasoned that software needed to be expressed on a computer readable format like a CD to be combinable. “Abstracted from a usable copy, code is intangible, uncombinable information, more like notes of music in the head of a composer than ‘a roller that causes a player piano to produce sound.’”
A signal is unlike an abstract form of software because the signal physically embodies the software. Like the Court in Microsoft held that software needed to be embodied in a physical medium to be more than a mere idea, a signal passes subject matter eligibility by being physically embodied in a computer-readable medium.
Software embedded in a signal is more than an intangible algorithm or idea. The medium makes the embodiment of the idea or algorithm an application to a real-world object that is new and useful. When it does so in a reproducible way, and can be ensured that the invention does not change, much like a non-transitory medium does not change, the signal should be patent-eligible.
The courts have upheld reproducible, transitory patentable subject matter in the past. In In re Hruby, the CCPA held that a transitory water fountain was eligible subject matter for a design patent. The court rejected the notion that the fountain was fleeting and held that it fit within the category of a manufacture. The court reasoned that even though the fountain comprised transient and fleeting water molecules, the overall fountain remained substantially constant when certain parameters were met: configuring the orifice, maintaining a certain water pressure and atmospheric conditions. Additionally, the water fountain although made up of a transient composition of matter was physical in nature. The court reasoned that it would not make consider the fountain appropriate subject matter when frozen, but not eligible when liquid. The court also reasoned that the water fountain was reproducible.
Similar to the fountain in Hruby, a signal can also be maintained at a substantially constant level, especially when the signal is digital. In the field of distributing data through the Internet or networking communications, information in the form of a signal, is highly constant and includes packets of information that is able to be verified down to the very bit. Like the water fountain, where the water pressure, the atmospheric conditions, and the orifice arrangements all when carefully maintained create a reproducible manufacture, so does the signal from one communication location to a destination when maintained have a very precise structure and composition of data.
A signal by the same analysis should also be a manufacture because of its reproducibility. In Ex parte Rice, the BPAI held that a signal claim with the language “electromagnetic signal” was eligible subject matter, despite being “transitory and ephemeral in nature.” A signal that, according to the court in Nuijten, is physical, transferrable, and reproducible, should like the water fountain in Hruby and the electromagnetic signal in Rice pass as an article of manufacture.
Because it is permissible to claim structures embodied in a storage medium, it is worth noting that the “difference between information storage and information communication is fundamentally only a difference in one’s inertial frame of reference.” The difference between a non-transitory medium (such as a CD) being patent-eligible, but a signal automatically ineligible because it is transitory does not make sense, especially when the invention can be conveyed to the computer in the exact same form. It does not make sense to disqualify the signal claim based solely on its transitory nature.
Proposed Signal Claims
It seems unlikely that the propagated signal, which has so many similarities to patent-eligible manufactures, have been killed for good, such claims rather just must be adapted. Arguably, the Federal Circuit in Nuijten could have categorized the signal as a manufacture, using an expansive view of subject matter. The category of manufacture is classically the catch-all subject matter category. Thus a manufacture includes “every article devised by man except machinery upon the one side, and compositions of matter and designs upon the other.” However, at the very least, assuming that the Federal Circuit was correct in Nuijten, a signal claim should be accepted when it incorporates the following limitations into it: physical, transferrable, and reproducible. Perhaps the court struck down the signal claim in Nuijten because it claimed a signal without any modifiers or limitations. The USPTO has issued 452 patents with “a claim having the exact phrase ‘computer data signal embodied in a carrier wave,’ the latest on September 11, 2007.” The “computer data signal” claim signifies that the signal is physical. Since in Nuijten a signal claim without any modifiers was physical, it can only be assumed that a “computer data signal” is physical also. Next, the signal can be transferred to computers because the claim is a computer data signal. Finally, the computer data signal is reproducible. Computer data is transmitted in blocks, followed by a parity that checks the integrity of the receiver’s data. One single bit error requires the retransmission of the entire block, ensuring that the content embedded in the signal is reproducible to the very bit. This is unlike other types of transmission such as voice or video, where errors are tolerated. Modifying the signal claim with “computer data” should convey the idea that the signal is reproducible.
Another signal claim that should pass the subject matter inquiry is “computer-readable signal.” This claim borrows language from the Beuaregard claim. If it can be established that “non-transitory” should not be a limitation to a software claim, then returning back to the pre-Nuijten claims of “a computer-readable medium . . . .” Kappos recently established that “a computer-readable medium” in its broadest reasonable interpretation includes a signal per se. It may be desirable to claim a “non-transitory computer-readable medium,” as recommended in the interim guidelines, followed by “a computer-readable signal” to receive protection for both types of media. A computer-readable signal claim should work to the extent that it is reproducible and transferrable. Even though some computer-readable signals may not be reproducible, most data transmissions are. For those transmissions that are not set up to trace their reproducibility, allowing a “reproducible” modifier should solve the problem. For example, “a reproducible computer-readable signal” ensures that the invention is fixed in much the same way that current software is fixed in tangible media.
“When the broadest reasonable interpretation of a claim covers a signal per se
, the claim must be rejected under 35 U.S.C. § 101 as covering non-statutory subject matter.” David J. Kappos, Subject Matter Eligibility of Computer Readable Media. 1351 OG 212 (Feb. 23, 2010).
 500 F.3d 1346, 1351 (2007).
 Id. at 1353, 1356.
 Id. at 1355.
 126 U.S. 455 (1888).
 Id. at 532–33.
 Id. at 532.
 See In re Nuijten, 500 F.3d 1346, 1353 (Fed. Cir. 2007) (holding that a signal implies with it a physical carrier).
 958 F.2d 1053 (Fed. Cir. 1992).
 Id. at 1059.
 See, e.g., In re Bernhart, 417 F.2d 1395, 163 USPQ 611 (CCPA 1969).
 Nancy Linck & Karen A. Buchanan, Patent Protection for Computer-Related Inventions: The Past, the Present, and the Future, 18 Hastings Comm. & Ent. L.J., 659, 677 (1996).
 Kuester, Horstemeyer & Santos, A New Frontier in Patents: Patent Claims to Propagated Signals, 17 J. Marshall J. Computer & Info. L. 75, 77 (1988).
 It is important to note that the PTO has never consistently advocated signal claims. In Interim Guidelines from the preceding year, for example, stated “it does not appear that a claim reciting a signal encoded with functional descriptive material falls within any of the categories of patentable subject matter set forth in Sec. 101.” 1300 OG 142, at 25 (Nov. 22, 2005), available at http://www.uspto.gov/web/offices/com/sol/og/2005/week47/patgupa.htm (last visited Apr. 1, 2010). Additionally, this example was removed shortly after posting it on the USPTO’s website. Email from Dan Santos, IP Attorney, to Trent Ostler, J.D. Candidate, Franklin Pierce Law Center (Apr. 1, 2010, 21:34 PST) (on file with author).
 Examination Guidelines for Computer-Related Inventions, available at http://web.archive.org/web/19980529122936/http://www.uspto.gov/web/offices/pac/dapp/oppd/compenex.pdf, at 39 (Mar. 28, 1996).
 Id. at 41.
 Nancy Linck & Karen A. Buchanan, Patent Protection for Computer-Related Inventions: The Past, the Present, and the Future, 18 Hastings Comm. & Ent. L.J., 659, 677–78 (1996).
 See, e.g., In re Nuijten, 500 F.3d 1346, 1353 (Fed. Cir. 2007) (citing Arrhythmia Research Technology, Inc. v. Corazonix Corp., 958 F.2d 1053, 1059 (Fed. Cir. 1992).
 See Dennis S. Karjala, The Relative Roles of Patent and Copyright in the Protection of Computer Programs, 17 J. Marshall J. Computer & Info. L. 41, 64 (1998) (“Program object code on a diskette is every bit as much a machine part as these hypothetical black boxes.”).
 For instance, a CD containing software is a tangible embodiment of the invention that can only be used by one person. Even though a computer can read the CD and the digital contents can be copied to another storage medium, this does not diminish the tangibility and rivalry of that particular CD with software.
 Dennis S. Karjala, The Relative Roles of Patent and Copyright in the Protection of Computer Programs, 17 J. Marshall J. Computer & Info. L. 41, 65 (1998).
In its executable form, the code exists as physical signals (high or low voltages or magnetic field strengths), not as ones and zeros that may be readable by humans. These physical signals may be used directly by the computer in the course of operations. For reasons of operational efficiency, however, these program signals are usually not directly used by the computer but rather are transferred from the diskette to other parts of memory, but the transfer is one to one and exact. . . . Consequently, while today the program does not directly govern computer operations from the diskette, its exactly transferred copy does.
 E.g, Ex parte Azuma, B.P.A.I. Appeal No. 2009-003902 (Sept. 14, 2009), available at http://des.uspto.gov/Foia/ReterivePdf?system=BPAI&flNm=fd2009003902-09-14-2009-1 (last visited Apr.5, 2010).
 Microsoft Corp. v. AT&T Corp., 550 U.S. 437, 449 (2007).
 See also In re Johnson, 589 F.2d at 206 (1978) (stating that Benson “applies equally whether an invention is claimed as an apparatus or process, because the form of the claim is often an exercise in drafting”); Andrei Iancu & Jeremiah Helm, Code on Disks and Hat Tricks: Is Computer Software on a Medium Really Patentable?, 90 J. Pat. & Trademark Off. Soc’y 97 (2008).
 Gottschalk v. Benson, 409 U.S. 63, 64 (1972).
 550 U.S. 437 (2007).
 Id. at 449.
 Id. at 451 n.12.
 But see In re Nuijten, 500 F.3d 1346, 1366 (holding that signals are unpatentable because they fail the tangibility requirement of being a manufacture).
 Andrei Iancu & Jeremiah Helm, Code on Disks and Hat Tricks: Is Computer Software on a Medium Really Patentable?, 90 J. Pat. & Trademark Off. Soc’y 97, 98 (2008).
 It is important to note that even though Hruby’s water fountain as a design patent relies on § 171 for subject matter, the only difference in language between § 101 and § 171 is “useful”:
101: Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions and requirements of this title. 35 U.S.C. § 101 (2008).
171: Whoever invents any new, original, and ornamental design for an article of manufacture may obtain a patent therefor, subject to the conditions and requirements of this title. 35 U.S.C. § 171 (2008).
Because the usefulness of software was never an issue in Nuijten, nor in other software patents, the subject matter concerns should be the same.
 Another term for fleeting is transitory. Dictionary.com, http://dictionary.reference.com/browse/fleeting (last visited Apr. 5, 2010).
 The court addressed the difference in language between article of manufacture and manufacture.
We fail to find in the opinion of the board majority any sufficient reason for holding the fountains are not ‘articles of manufacture.’ If, per chance, the board was attempting a distinction between ‘manufactures,’ which it seemed to think the fountains are, and articles of manufactures, we think that supposed distinction was fully disposed of by our predecessor court . . . in In re Hadden (holding that there is no difference between a manufacture and an article of manufacture).
 Ex parte Rice, Appeal No. 2002-1554 http://des.uspto.gov/Foia/ReterivePdf?system=BPAI&flNm=fd021554 (B.P.A.I. Mar. 13, 2003)
 Id. at 2; accord O’Reilly v. Morse, 56 U.S. at 114–19; In re Breslow, 616 F.2d 516 (CCPA 1980).
 Michael P. Frank, The Physical Limits of Computing, 4 Computing in Science & Engineering 16, 24 (2002).
 Professor John Duffy at George Washington remarked:
Yet . . . there will still be nothing to stop Philips from claiming transport media (e.g., wires, cables, and fibers) containing the relevant signal. True, such claims may not be able to cover free space propagation of an electromagnetic signal, but that may matter little. Current technology requires electronic circuitry having physical wires to generate and to receive an electromagnetic signal. Moreover, many, perhaps even most, electromagnetic signals are today being transported by fibers, cables or wires. Thus, even under the PTO’s interpretation of § 101, Philips should be able to achieve much of its intended objective, provided that the company observe some formalisms.
 According to Chisum, manufacture “is the residual class of ‘product’ patent – encompassing all man-made items not found in substantially the same form in nature that are neither machines nor compositions of matter.” Chisum on Patents § 1.02.
 Id. (quoting I.W. Robinson, The Law of Patents for Useful Inventions, 270 (1890)).
 Posting of luke84 to http://ip-updates.blogspot.com/2007/09/signal-claims-not-patentable-subject.html (Apr. 2, 2010, 21:29 EST).
 See In re Nuijten, 500 F.3d 1346, 1356 (Fed. Cir. 2007) (holding that a signal is physical).
 The transmission that carries a data signal is governed by digital transmission standards that ensure that the sender’s and receiver’s content is the same. David Russell Smith, Digital Transmission Systems, at 13 (2003). The FCC authorizes carrier services and sets technical and operational standards. Id.
 Id. at 57.
 David J. Kappos, Subject Matter Eligibility of Computer Readable Media, 1351 OG 212 (Feb. 23, 2010), available at http://www.uspto.gov/patents/law/notices/101_crm_20100127.pdf (last visited Apr. 3, 2010).
 Such as voice and video transmissions. This is in contrast to data transmissions, that are governed by digital transmission standards that ensure that the sender’s and receiver’s content is the same. David Russell Smith, Digital Transmission Systems, at 13 (2003). The FCC authorizes carrier services and sets technical and operational standards. Id.