Relative time (vs. calendar)
Sometimes variables don't refer to specific calendar time steps of your model (Jan 2022, Feb 2022) but refer to relative time (Month 1, Month 2). Some examples:
You likely don't think of retention rate for January, February and March, but rather for a customer's first, second, and third month.
Sales person (or other productivity driven role) ramp time
When you add a new sales person you probably don't want to assume that they will be 100% productive in their first month but rather that they ramp up at some percentage over time.
You can turn variables into relative time variables in the context menu. This will show the relative time step in the cells (e.g. Mo 1, Mo 2), as well as in the drop-down in Presentation mode.
Note: If you import or reference a relative time variable in a model, it will always obey relative time, i.e. it will align with the time step it is associated with, regardless of the model start date. For example, if you have Month 1 Retention of 100% with a model start date of Jan 2021, and then import that variable into a model that starts in Jan 2022, that Retention variable will still align with Month 1 (which is now Jan 2022 in calendar time).