The bill also would modify provisions related to the areas and the types of practice in which scholarship recipients may fulfill their service obligations. These modifications are necessary to: Assure that particular populations or institutions are not deprived of needed National Health Service Corps placements if the overall physician supply in a shortage area increases. and Assure that physicians who are able to serve their payback time in a private practice setting are meeting their statutory obligation to serve all medicare and medicaid recipients and to serve others without regard to their ability to pay. Title IV would extend for 4 years the programs of support for health maintenance organizations and migrant and community health centers. The effect of the community health center extension is not to extend the primary care block grant option. This is done because no State has actually put that block grant into operation and the Department of Health and Human Services has been enjoined from proceeding with implementation because it had failed to administer the program in accordance with the statute.