---
title: "PFD/DFR/STR Calculation Engine Specification for SIFPro & IMS SIS"
slug: "pfddfrstr-calculation-engine-specification-for-sifpro-ims-sis"
updated: 2026-10-27T23:12:43Z
published: 2026-10-27T23:12:43Z
canonical: "ims-handbook.cenosco.com/pfddfrstr-calculation-engine-specification-for-sifpro-ims-sis"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://ims-handbook.cenosco.com/llms.txt
> Use this file to discover all available pages before exploring further.

# PFD/DFR/STR Calculation Engine Specification for SIFPro & IMS SIS

## Summary

The IMS SIS & SIFpro SIF Analysis tools are used to demonstrate whether the SIL (PFDAV or DFR) requirements of a SIF design can be met. The objective of the report below is to provide a detailed description of how the IMS SIS / SIFpro calculation engine works and how user input from the User Interface affects PFD/DFR calculation engine outcomes.

[PDF document](https://cdn.document360.io/e492a0e0-a4ba-4aca-8fc6-76b95f91fdf3/Images/Documentation/PFD-DFR-STR%20calculation%20engine%20specification%20for%20SIFPro%20and%20IMS%20SIS.pdf?sv=2026-02-06&spr=https&st=2026-10-28T14%3A23%3A49Z&se=2026-10-28T15%3A23%3A49Z&sr=c&sp=r&sig=Oam%2FzY3YtAHsUDpGXGihmwoeiHFalCNQ56%2FyK48GtGQ%3D)