Pieces of the FedReg Puzzle by Shirley Maxwell Federal income-tax credits for historic-building rehabilitation almost always require a long, bewildering journey through a lush jungle of federal regulations. But for those whose buildings qualify, the trek through the tangled underbrush of preservation FedRegs can pay off handsomely. The key pieces of the FedReg puzzle follow. Begin at Your SHPO If you want to get a building listed in the National Register of Historic Places, or to find out if its neighborhood is slated to become a historic district, the State Historic Preservation Office (SHPO) is the place to begin. SHPO officers, one per state, nominate historic properties and districts to the National Register. For your SHPO officer's name, contact your local preservation organization or