The congressional Physician Payment Review Commission (PPRC) has been in the forefront of advocates for a national data system (PPRC, 1992, 1993). In its 1992 annual report, PPRC described an "all-patient database" [emphasis in the original], conceptualized as a "network of local or regional data processing centers ... to streamline the transfer of administrative information for payment and service-use tracking purposes" (p. 269). The report goes on to posit "parallel organizing entities ... to coordinate the use of these data [and] the data processing centers and the organizing entities would make up an all-patient data network" (p. 269). The commissioners also envisioned the network evolving into a "means to link and assimilate more detailed clinical information." Although the general thrust of the PPRC idea is consonant with the long-range views of this IOM committee, the specific understanding of what a database or network is differs. In defining an all-patient database, the commissioners appear to have in mind what this committee terms inclusiveness; what the PPRC report lays out as "core data elements'' in that database approaches what the IOM report calls comprehensiveness.