An Act amending the act of August 24, 1963 (P. L. 1175, No. 497), known as the "Mechanics' Lien Law of 1963," adding and amending definitions; further providing for rights to a lien, for certain cases when a lien is not allowed, for assignment of claims, for waivers of liens, for owner's right to limit claims, for contents of claims, for owner's right to retain funds, for notice of claims, for contractor's duties, and for owner's additional remedies; and requiring notice of claim by a laborer.