The Fairfax County School Board unanimously approved last night a change in its student assignment policy that puts added responsibility on parents to prevent the transfer of students for athletic or other extracurricular reasons.

Parents will now be required to sign a statement at the time of a transfer request promising that the change is not being made to move a son, for example, to a better football team or marching band. The change also clarifies the situations under which a transfer may be made, which include child care or academic reasons.

Board member Gerald Fill labeled the change mere "administrative streamlining" and said it fails to address the question of how enforceable are rules aimed at prohibiting the recruitment of high school athletes.

The change was recommended by a task force assigned after a Mount Vernon High School basketball team was sanctioned two years ago for recruiting players from Alexandria. The change approved last night does not address the question of transfers to county schools from other jurisdictions.

According to assistant superintendent John Schrek, who headed the task force, an estimated 25 percent of the 5,000 or so transfers requested within the school system each year are at the high school level. He said he had no doubt that a "small number" of those transfers are requested by parents so that a child can play on a better athletic team or school band. Schrek says he believes that making parents sign a statement will "sensitize them so there won't be automatic sign-off on these things."

After the meeting, board member Fill, in whose Mount Vernon school district the penalties for recruitment were imposed and who asked that the task force be formed, said the group's recommendations had not gone far enough.

"This change doesn't affect the criteria for placement, it just adds the parental disclaimer," he said, adding that the task force did not answer fundamental questions about the enforceability of such rules or the legality of sanctioning school athletic teams, rather than school officials, when such rules are broken.