Who is that woman behind the mask? Umpire Pam Postema. Veteran of top minor-league level eager to move up to baseball majors

Pam Postema accepts verbal abuse and sneers from men as a matter of course most every day she works. It's all part of her job. Postema is a professional baseball umpire -- the first woman to reach the Class AAA level, just one step below the major leagues. So arguments go with the territory, but of course her calls are always the last word no matter how much a player, coach, or manager complains.

Off the field, Pam is a warm, intelligent, outward individual with a firm belief that a woman can be just as good as -- if not better than -- any man as an umpire. On the field she is strict and firm. And her calls are made with lightning speed.

``Oh, no, not a woman umpire,'' Postema recalls one coach saying when he saw her getting ready to work a game in Tempe, Ariz. The coach raised his hands skyward, then placed them atop his head which he shook from side to side. Yet, during the game he offered not a single word of criticism.

Pam is now in her third year in the Triple A Pacific Coast League and her ninth season of umpiring overall. She anticipates becoming the first ``woman in blue'' in the major leagues, which she hopes happens soon.

``I love every moment of my work,'' says Postema, who was born in Willard, Ohio, but now makes her home in Phoenix. ``During the winter months I have been umpiring in Arizona, Hawaii, and Puerto Rico. And I most always find time to either relax or shop in the cities I work.''

Pam is not the first female to umpire professionally. Several years ago Bernice Gera, a Jackson Heights, N.Y., housewife, took baseball to court and won the right to work in the New York-Pennsylvania League. She turned out to be more women's rights advocate than would-be umpire, however, quitting after working the first game of a doubleheader.

Then there was Christine Wren, who umpired for a while in the minor leagues and even worked some big league exhibition games. Wren said at the time that she planned to make umpiring her career and hoped to reach the major leagues, but a couple of years later she retired and went into a more conventional job.

Postema, meanwhile, had no particular ambitions along these lines while growing up. She played some fast-pitch softball as a teen-ager, but had never umpired at any level when one day an ad for an umpiring school in Daytona Beach, Fla., caught her eye.

She had an industrial job and was thinking about going to college, but something led her to look into the umpiring possibility instead. She made three applications to the school without getting a single reply back. Finally she went there in person and asked for just a chance. She was given that chance and became the 17th best in her class of 130 students.

That record landed her a job in the Gulf Coast League for rookie players. She spent two years there, another two seasons in the Class A Florida State League, and two more in the Class AA Texas League before being moved up to the PCL in 1983.

The next step, of course, would be the big one. And Postema is eager for the challenge.

``Why shouldn't there be a woman umpire in the major leagues?'' she asks.

``A woman ran for vice president of the United States. Another became a successful astronaut. Women are successful in the business field and in science. These fields were once dominated by men.

``I hope to be the first woman umpire in the major leagues. I am ready.''