(This was intended for making VSMs with multiple languages available, where the initial load addresses could remain static, so for example they would not require changes to code in a microcontroller, and only the values pointed to in the VSM needed changing. In practice it doesn't seem to have ever been used, as it doesn't work when more than one VSM chip shares a bus, which is what was done in most cases.)
The purpose of this method was to develop VSMs with multiple languages, keeping initial load addresses unchanged to avoid altering microcontroller code. However, in actual use, it has not been employed due to its failure when multiple VSM chips share a common bus.