The Federal Reserve Board proposed rules to limit the time banks can hold customers' checks before making funds available. Under the proposal, funds must be available the next day for certain types of checks such as Treasury checks. For other, local checks, funds must be available by the third business day after deposit and for more distant checks by the seventh business day. This would apply beginning Sept. 1, 1988. On Sept. 1, 1990, the delay in availability would be shortened to the second and fifth business days respectively, the Fed said.