Using the RAMP data in the IBIS you can compare the Slew Rate between SLOW and FAST, try to understand the document using the notes and legends provide especially "Naming Conventions" in the upper part of the document and be able to read and understand the data provided.
When checking the IBIS model, one should be familiar of the naming conventions of the I/O model. As an example, you can check the ramp data for MachXO2.