Index based lease assessment

Summary:

Can anyone explain how the Index based lease assessment works?

1. Do we need to load WPI or CPI anywhere in the system which the program can refer to?
2. If answer to above is no, can you explain how the system works?

Content (please ensure you mask any confidential information):

NA

Version (include the version you are using, if applicable):

23D

Code Snippet (add any code snippets that support your topic, if applicable):

NA