In Commercial Union Ins. Co. v. Lewis & Roca, 183 Ariz. 250, 254, 902 P.2d 1354, 1358 (App.1995), attorneys at a law firm had erroneously overlooked a relevant case in advising a client about an insurance coverage issue. Id. at 252, 902 P.2d at 1356. However, a different attorney representing the client in subsequent litigation advised that the case was distinguishable. Id. at 253, 902 P.2d at 1357. Until the court in that litigation ruled against the client and found the overlooked case controlling, the client had not suffered damages even though the negligence had occurred some years before. Id. at 256-57, 902 P.2d at 1360-61. As the court noted in Commercial Union, until that ruling, "the coverage issue was an open question." Id. at 257, 902 P.2d at 1361. Thus, it was in this context that Commercial Union used "irremediable or . . . irrevocable" to describe the "actual and appreciable" harm a plaintiff must sustain before a cause of action for professional negligence can accrue. Id. at 254, 902 P.2d at 1358.