packages made up and mailed by the Letter Registrar to inform various sections of he mailing list on the next service they might be interested in, having already done something. There could be a book info packet for a person who has just bought a book, a test info packet for a person just tested, a PEinfo packet for the person who has just done a PE, etc., etc. In each case it offers the next service. (HCO PL 4 Feb 61)