The price is the price
The county records the date of the last transfer and the amount, and the report prints both. There is no inference involved. In Oakland the same question has to be answered sideways, by reading the documentary transfer tax and computing backwards from it, and in San Francisco it cannot be answered at all.
Zero is not a price
A great many transfers record an amount of zero: government transfers, transfers between family, corrections of a deed. The report drops those rather than printing a building that sold for nothing. City Hall last changed hands on 13 December 1995 with no amount recorded, and the report shows the date and leaves the price blank, which is the honest pair.
What the class code means
The county files every parcel under a numeric class and publishes its own grouping of them: the 400s are commercial, the 500s residential, the 600s publicly owned, the 300s industrial and the 100s agricultural, with a separate code for vacant land in each. The report prints the county's grouping rather than inventing its own.
Counts run 7 September 2026.