From Simple Wiki

ISIS is the unfortunately named driver standard developed by Pixel Translations years before the acronym (which stands for “Image and Scanner Interface Specification”) had any jihadist connotations.

ISIS provides a more standardized interface for high-speed scanners, and is often required to scan at the scanners rated speed.

ISIS settings can also be saved to the SimpleIndex Job File to ensure the optimized scanner settings are retained between sessions or distributed to multiple workstations.

A Professional license or the ISIS driver add-on is required to enable ISIS scanning.