In reviewing a writ of mandate, what is the scope of the review?

"In reviewing the trial court's ruling on a writ of mandate (Code Civ. Proc., 1085), the appellate court is ordinarily confined to an inquiry as to whether the findings and judgment of the trial court are supported by substantial evidence. [Citation.] However, the appellate court may make its own determination when the case involves resolution of questions of law where the facts are undisputed." (Saathoff v. City of San Diego (1995) 35 Cal. App.4th 697, 700, 41 Cal.Rptr.2d 352.)