SAN FRANCISCO — Synopsys Inc. and Mentor Graphics Corp. have agreed to cross-license each other's entire EDA tool sets in order to test them and make sure they work together well in design flows.

The development continues the increasing cooperation between Synopsys and Mentor, which has seen the companies start a design-reuse partnership to explore system-on-a-chip design issues, and the cosponsoring of the writing and publication of the Reuse Methodology Manual. The latest agreement adds to the list of other multi-vendor programs such as Synopsys' In-Sync program, Mentor's OpenDoor programs, program-specific licensing and joint-marketing agreements.

"Customers are constantly requesting a higher level of cooperation between EDA vendors to better address the needs of design tool interoperability," said Aart de Geus, chairman and chief executive officer of Synopsys. "Together with Mentor Graphics, we are responding to them."

The collaboration is not an OEM agreement that allows the companies' sales forces to sell each other's tools, de Geus said, but "we can go to the customer and say, 'Buy from Synopsys and Mentor.' "

De Geus was asked if Synopsys would welcome the opportunity to enter a similar cross-licensing arrangement with Cadence Design Systems Inc. in the interest of promoting tool interoperability. "In general," he responded, "we are entering an age where broad cross-licensing happens anyway."

Wally Rhines, president and chief executive officer of Mentor Graphics, said his company already had a similar arrangement with Cadence.

Speaking specifically about Cadence, de Geus said he was prepared to enter such an agreement, but added that he reserved the right not to enter such agreements with companies that he viewed as heavy competitors of Synopsys.