Definition - What does Adjustment Index mean?
An adjustment index is a data modification such as a numerical adjustment to the rate of interest paid on a mortgage of a set number of years. The index would keep track of all the adjustments that were made to a base number or calculation in order to act as a historical reference and for legal implications such as assessing the amount of tax or interest paid.
Justipedia explains Adjustment Index
An adjustment index can be used to figure out what the average change was over a set number of years, and can act to form the basis of new transactions and the charges that are attached.