law in force. Where a title has been enacted into positive law, a court may neither permit nor require proof of the underlying original Acts of Congress. The distinction between enacted and unenacted titles is largely academic because the Code is nearly always accurate. The United States Code is routinely cited by the Supreme Court and other federal courts without mentioning this theoretical caveat. On a day-to-day basis, very few lawyers cross-reference the Code to the Statutes at Large. Attempting to capitalize on the possibility that the text of the United States Code can differ from the United States Statutes at Large, Bancroft-Whitney for many years published a series of volumes known as United States Code Service (USCS), which used the actual text of the United States Statutes at Large; the series is now published by the Michie Company after Bancroft-Whitney parent Thomson Corporation divested the title as a condition of acquiring West. Uncodified statutes Only "general and permanent" laws are codified in the United States Code; the Code does not usually include provisions that apply only to a limited number of people (a private law) or for a limited time, such as most appropriation acts or budget laws, which apply only for a single fiscal year. If these limited provisions are significant, however, they may be printed as "notes" underneath related sections of the Code. The codification is based on the content of the laws, however, not the vehicle by which they are adopted; so, for instance, if an appropriations act contains substantive, permanent provisions (as is sometimes the case), these provisions will be incorporated into the Code even though they were adopted as part of a non-permanent enactment. Versions and history Early compilations Early efforts at codifying the Acts of Congress were undertaken by private publishers; these were useful shortcuts for research purposes, but had no official status. Congress undertook an official codification called the Revised Statutes of the United States approved June 22, 1874, for the laws in effect as of December 1, 1873. Congress re-enacted a corrected version in 1878. The 1874 version of the Revised Statutes were enacted as positive law, but the 1878 version was not and subsequent enactments of Congress were not incorporated into the official code, so that over time researchers once again had to delve through many volumes of the Statutes at Large. According to the preface to the Code, "From