the below description is pasted from the “Site Notes” of the source:
Salary data are identical to those from public records requests by the San Francisco Chronicle. The Chronicle described the 2005 data as follows, which probably applies to later data as well:
In addition to salaries, total pay includes overtime, bonuses, housing allowances, relocation allowances, administrative stipends, revenue sharing and more than a dozen other types of cash compensation. It does not include health or retirement benefits.
The Sacramento Bee explains the numbers further (paraphrased):
Results are the actual amounts paid to workers during the year, according to the UC system. Since this data looks back in time -- it has to for overtime to show up -- those who worked only part of the year will see their actual earnings for the year, not how much they will eventually make over 12 months. Gross pay includes overtime, bonuses, housing allowances, sick leave payout, vacation payout and multiple other forms of cash compensation. Some workers promoted toward the end of the year will see their old job titles listed here.