Earlier in the month, Apple had filed additional claims and MOSAID, a Canadian company, said it would also Sue HTC, and Sony Ericsson, for patent infringement.

Alternatively, an applicant can take the patent the PTO has awarded and at the same time seek additional or broader claims arising out of the same patent application.

On the other hand, such differences can provide additional indicia of likelihood of patent litigation, and help companies to identify the riskiest patents prior to the time of the litigation.