One of the clauses in the $13.2 million offer sheet Moses Malone signed with the Philadelphia 76ers was ruled invalid yesterday.

Kingman Brewster, a court-appointed special master who hears disputes arising from the settlement of the Oscar Robertson antitrust suit, also ruled the Houston Rockets, Malone's team the past six years, have the right of first refusal for any offer sheet. The 76ers had contended Houston did not have that right.

Brewster heard testimony yesterday in New York concerning the offer sheet and then took the matter under advisement.

In addition to the base salary of $1.6 million a year for six seasons and a $1 million signing bonus -- all in cash -- there are six clauses in the offer sheet, five of which the National Basketball Association believes are designed to prevent Houston from matching the offer. Malone became a free agent this summer when his six-year contract with Houston expired.

Brewster said he will rule on the other clauses by Saturday or Monday. If the 76ers are found to be in violation of NBA rules, the clauses will be struck. A league spokesman also said the team could be fined as much as $250,000. Houston originally had 15 days, or until Saturday, to match Philadelphia's offer; now they will have 24 hours from the time of Brewster's rulings to match it.

Brewster ruled Houston does not have to match the clause calling for Malone to be paid a bonus if he does not earn a certain amount in endorsements. He also denied the contention by the 76ers and attorneys for Malone that the Rockets, who were recently sold, cannot transfer their right of first refusal from one ownership to another.

Another clause the NBA objects to would give Malone $100,000 each year that none of his teammates makes the league's top 10 in scoring, rebounding, steals or assists. The 76ers had someone in each of those categories last season; aside from Malone, Houston had no one among the league leaders.

Another clause would give Malone $200,000 for each of the first three seasons the team he signs with does not rank in the top six in the league in road attendance. Philadelphia was second behind Boston last season; Houston was eighth.

Another calls for Malone to get 5 percent of his team's gross receipts for the season in excess of $4 million. This could discourage the Rockets from matching the offer sheet, then trading Malone to a team with high attendance totals, such as Seattle, Los Angeles or Boston.

Among those testifying at the all-day hearing were attorneys representating the NBA, the NBA Players Association, Malone and the past and incoming owners of the Rockets. Also present were several 76ers representatives: owner Harold Katz, General Manager Pat Williams, Coach Billy Cunningham, Business Manager John Nash and attorneys for the team.