San Francisco--Developers of marketing technologies said Monday they've agreed to develop an open standard for creating, storing and exchanging data about Web users. Led by such companies as net.Genesis, Cambridge, Mass., a consortium of Web marketing companies is working on what's called Customer Profile Exchange or CPEX - due to be released as a specification in June 2000. An open specification for customer profiling has major implications for business marketers. It means sales force, call center, purchase history, Web inquiries and other forms of data would be easier to integrate into a single customer profile. Other major members of the consortium are Siebel Systems, San Mateo, Calif., and Vignette, Austin, Texas.