Definition from Nolo’s Plain-English Law Dictionary
The rule under which the U.S. Copyright Office allows software object code to be deposited in connection with a computer program registration. Under the rule there is an express understanding that doubt exists as to whether the code qualifies for copyright protection should litigation later occur. In essence, the Copyright Office is saying, "We will let you deposit object code, but since we can't read or understand it, we won't commit ourselves as to its copyrightability." If the registration is accomplished under the rule of doubt, the copyright owner may be unable to claim the presumption of ownership -- an important benefit of registration -- should the issue end up in court because of an alleged copyright infringement.