MEXICO CITY, NOV. 6 -- Mexico and the United States signed a new bilateral "understanding" today committing the two countries to immediate negotiations on a wide range of cross-border trade conflicts.

Though much more modest in scope than the United States' agreements with Canada and Israel, the understanding was compared to those accords by U.S. Trade Representative Clayton Yeutter and Mexican Commerce and Industry Secretary Hector Hernandez. No other countries have bilateral accords governing trade relations with Washington, they said.

The agreement will help Mexico take better commercial advantage of "its geographical position next to the largest and, why not say it, the most open market in the world," Hernandez said after he and Yeutter signed the document at a morning ceremony.

The understanding establishes what it terms "a framework of principles and procedures for consultations regarding trade and investment relations."

The document states that Mexico and the United States must begin formal negotiations within 30 days of the filing of a trade or investment complaint by either government. It also commits the two nations to start substantive trade negotiations in the next 90 days on seven traditionally contentious subjects: textiles, agricultural products, steel sales, electronics goods, foreign investment, intellectual property rights and the regulation of service industries.

"We can't resolve all our trade problems with an understanding of this kind," Yeutter said, speaking in Spanish to the local press. "That would be impossible. But this is an important stage in the strengthening of our trading relationship."

Mexico, Hernandez acknowledged, hopes to use the talks to gain a bigger U.S. market share for its steel, textiles and farm products. The United States is said by officials to be primarily interested in changing Mexico's investment and patent rules, though it also is seeking better market access for U.S. consumer goods.

The trade accord was hailed by business leaders from both sides of the border as a historic breakthrough in bilateral economic relations. "It wasn't long ago that Mexico wasn't interested in any kind of a bilateral agreement," said Rodman C. Rockefeller, cochairman of the private Mexico-U.S. Business Committee.

Yeutter expressed hope that the agreement would spur bilateral trade substantially beyond its current $30 billion-a-year level. The U.S.-Mexican framework accord and the recent U.S.-Canadian free trade agreement "are two good examples of how to improve trade relations without legislation," he said.

Hernandez and Yeutter stressed that Mexico may be decades away from a bilateral free-trade accord on the U.S.-Canadian model, however. "Economic conditions in Canada are in many ways comparable with those in the United States, which is not exactly the case with Mexico," Hernandez said. "The Mexican economy is not ready now, and will not be for a long time, to enter into a trading relationship with the United States based on equal treatment."

Some of the talks called for by the accord are under way. In steel, the product area where negotiators have been making the most progress, the United States is expected to announce an approximately 10 percent increase in Mexico's import quota within a few weeks, businessmen said.