Registering Your Idea Our Invention Protection Expert shows you the ins and outs of the Disclosure Document Program.

Q: I filed a registration form with the Patent and Trademark Office (PTO) on an idea approximately two years ago. The expiration date is quickly approaching. Can I extend the registration?

A: I believe by "registration form" you mean you filed a disclosure document (DD) with the Patent and Trademark Office under its Disclosure Document Program (DDP). While a DD is a type of registration for an invention, it doesn't provide as many rights as most inventors think it does.

The DDP is simply an invention conception date recording service where the PTO (or either the Sunnyvale, California, Patent Depository Library [PDL] or the Detroit PDL) will witness anyone's invention description for a $10 fee. An inventor sends a copy of a description and drawings of the invention to the PTO (or PDL). The inventor should also include the $10 fee and a cover letter requesting the DD be accepted under the DDP and be preserved for two years. The description and drawings of the invention should have a title and be detailed and complete enough to enable anyone having ordinary skills in the field of the invention to make and use the invention.

The PTO (or a PDL) will stamp and number the DD, then send the inventor a form letter acknowledging the DD and indicating its number and filing date. They'll retain the document for two years, then discard it, unless the inventor refers to it in a patent application. An inventor can't get an extension on this two-year period, except by filing an actual patent application with a letter in the patent application referring to the DD by its number, title and filing date, and asking that the DD be retained in connection with the application.

If properly done, a DD provides evidence of the identity of the inventor and the date of conception of the invention. However, this evidence is useful in only two situations, both of which may be encountered only while a patent application is pending:

1. If the PTO declares an interference-a proceeding to determine priority between two patent applications on the same invention. Then the DD can be used to prove priority of invention.

2. If the PTO cites a reference with an earlier date against a patent application. In this case, the inventor can use the DD to antedate and eliminate the patent as a "prior art" reference. However, in both situations, the inventor must also prove that he or she was "diligent" in filing the patent application or in building and testing the invention.

In addition to its limited usefulness, another disadvantage of the DD is that an inventor can obtain the document's benefits for free by simply signing, dating and getting at least one (preferably two) witnesses to sign and date a description of the invention. Since it's good practice to do this anyway, I feel the DD's additional value is negligible. I recommend inventors use the DDP that only if they don't have any suitable witnesses available.

There are many other pros and cons to the DDP an inventor should consider carefully. See chapter three of Patent It Yourself for a full discussion.

David Pressman, a practicing intellectual property attorney, is author of the bestselling bookPatent It Yourselfand the interactive software program Patent It Yourself, both published by Nolo Press. Formerly an electronic engineer, David has more than 30 years' experience in the patent profession-as a patent examiner, a columnist for EDN Magazine and a patent law instructor at San Francisco State University. Patent It Yourself can be obtained in bookstores (brick-and-mortar and online), from the publisher (www.nolo.com) and through David's Web site (www.PatentItYourself.com).

The opinions expressed in this column are those of the author, not of Entrepreneur.com. All answers are intended to be general in nature, without regard to specific geographical areas or circumstances, and should only be relied upon after consulting an appropriate expert, such as an attorney or accountant.