McMinnville Historic Zoning Commission members have initially approved changes to guidelines that make the rules more enforceable. The measure requires one more vote.Commission member Rachel Killebrew wants to remind downtown property owners the guidelines are in place to protect their property values.“Nationwide, buildings retain their value much better when they are in a historic district and if their owners comply with the rules for their building,” said Killebrew. “These changes will help to increase the value of their building and maybe we can get better compliance.”Most changes to the guidelines were removing the permissive words of “should” and “may” and replacing those with mandatory words of “shall” and “must.”