Section 21601 - Definitions(a) For purposes of this part, "decedent's testamentary instruments" means the decedent's will or revocable trust.(b) "Estate" as used in this part shall include a decedent's probate estate and all property held in any revocable trust that becomes irrevocable on the death of the decedent.Added by Stats. 1997, Ch. 724, Sec. 34. Effective January 1, 1998.