Litigation between PE Biosystems Inc. and rival sequencing equipment producer Amersham Pharmacia Biotech Ltd. last week moved one step forward as a California court accepted Amersham's definitions of disputed claims in U.S. Patent No. 5,688,648, a patent related to the use of energy transfer dyes that is licensed to Amersham. While Amersham's patent infringement claims wait to be addressed, however, PEB is on the way