The Homœopathic Pharmacopœia Revision Service, also known as the subscription service began in December, 1988. One or two revisions are published each year. The current purchase includes updates through December of the current year. These revisions contain revised material from the Homœopathic Pharmacopœia of the United States, Eighth Edition, Volume 1 published in 1979 with is no longer official. Traditionally, the HPUS was published as a hard cover text with revisions as necessary, generally every decade. However in the mid 1980's, the HPCUS resolved to change the format of the HPUS to a Revision Service that would be updated annually. The revision service was first published in 1988 and has been updated once or twice yearly since inception. Thus a subscriber should purchase the HPUS basic volume and annual subscriptions thereafter. The HPUS is published in binder form to facilitate ease of updating.