In theory the system was simple.
Liber Assedationis recorded the ownership of property.
Liber Vastarum recorded changes in ownership.

Again in theory, every time a property changed hands (sale, inheritance etc) an entry was made in Liber Vast. A corresponding entry was supposed to be made in Liber Assed but was not always done immediately. Many years could elapse before Liber Assed was brought up to date and the property may have changed hands several times in the meantime.

Unfortunately, there is no cross reference that I know of between the two.

As Michael pointed out, the various figures indicate the proportion of Lord's rent paid by the parties.