Internet advertising network 24/7 Media Inc. said it filed suit against DoubleClick Inc. alleging patent infringement. At issue is the use by DoubleClick, which is widely seen as the leader in the online advertising market, of a technology for DoubleClick's DART ad serving system that enables it to target specific ads to certain users based on usage patterns. New York-based 24/7 Media said the suit, filed in federal court in New York, seeks to bar DoubleClick from further infringement as well as unspecified monetary damages. Elizabeth Wang, DoubleClick's general counsel, said the company had not yet seen the complaint, but said that based on its initial review of the patent, "we believe that any claim of infringement would be baseless." Shares of 24/7 closed unchanged at $20.88, and DoubleClick rose 88 cents to close at $62.81, both on Nasdaq.