The Securities & Exchange Commission's new complaints about poor record-keeping in the $3 trillion Treasury securities markets mark the agency's latest move to enlarge its regulatory reach. The agency told Congress that handwritten bid slips and other irregularities hampered its probe of such wrongdoing as last summer's Salomon Brothers Inc. scandal. Chairman Richard C. Breeden says the SEC needs better "audit trails." But Treasury and Federal Reserve officials continue to resist SEC regulatory advances. They say all the agency was able to turn up with 190 subpoenas was a few examples of "whited-out" entries on bid sheets. Treasury and the Fed fear that additional regulation would drive up the government's borrowing costs.