To the Editor:

I noticed the following paragraph in the ''Topics'' section of the Sept. 29 editorial page:

Is no Washington name exempt from shorthand? One, maybe. The Chief Magistrate responsible for executing the laws is sometimes called the POTUS.

The nine men who interpret them are often the SCOTUS. The people who enact them are still, for better or worse, Congress.

According to the information available to me, and which I had assumed was generally available, for over two years now SCOTUS has not consisted of nine men. If you have any contradictory information, I would be grateful if you would forward it as I am sure the POTUS, the SCOTUS and the undersigned (the FWOTSC) would be most interested in seeing it. SANDRA D. O'CONNOR, Justice of the Supreme Court of the United States, Washington, Oct. 5, 1983