Is there an exception to the "one final judgment" rule?

One exception to the "one final judgment" rule codified in Code of Civil Procedure section 904.1 is the so-called collateral order doctrine. Where the trial court's ruling on a collateral issue "is substantially the same as a final judgment in an independent proceeding" (In re Marriage of Skelley (1976) 18 Cal.3d 365, 368), in that it leaves the court no further action to take on "a matter which . . . is severable from the general subject of the litigation" (In re Marriage of Van Sickle (1977) 68 Cal.App.3d 728, 735), an appeal will lie from that collateral order even though other matters in the case remain to be determined. (Day v. Papadakis (1991) 231 Cal.App.3d 503, 508.) Lennane relies on this exception to the "one final judgment" rule, but his reliance is misplaced.