In Holt v. Workers' Comp. Appeals Bd. (1986) the Compensation Appeals Board calculated the permanent disability of a boiler room tender at the Susanville Prison by using an "occupational variant" labeled "stationary engineer/boiler room tender--custodial duties." Arguing that he was entitled to greater benefits by application of a higher occupational variant for other employees having "custodial duties," the employee petitioned for writ of review. (Id. at pp. 1259-1260.) He asserted that administrative regulations requiring California Department of Corrections (CDC) employees "to prevent escapes or disorder, report rule violations, and to maintain the security and safety of the institution" establish a conclusive presumption that all CDC employees have custodial duties. (Id. at p. 1261.) Holt disagreed, explaining that CDC regulations indicate custodial duties may be imposed on "all employees" of CDC only in emergencies. Because the employee presented no evidence that he ever actually performed custodial duties, he was not entitled to the greater benefits received by CDC employees who perform such duties. (Id. at pp. 1261-1262.) Holt did not reach the question whether preventing escapes or disorder, reporting rule violations, and maintaining the security and safety of the institution constitute custodial duties. In dicta, Holt noted it would be absurd to adopt the conclusive presumption sought by the employee, explaining that to do so "would eliminate any occupational distinction among [CDC] personnel for disability rating purposes--i.e., clerical personnel or kitchen staff would be rated on the same disability level as the prison guards. the inappropriateness of such a rating scheme is obvious." (Holt, supra, 187 Cal. App. 3d at p. 1261.) However, this observation was directed to the claim that there was a conclusive presumption that all CDC employees perform custodial duties, and addressed distinctions among CDC occupations for purposes of permanent disability ratings. Holt did not consider the entirely different question whether the Legislature intended the "heart trouble" presumption of section 3212.2 to apply to all CDC employees who perform custodial duties