diff --git a/specifications/README.md b/specifications/README.md
index 02eb4da1e58455372e9e56db111fc87b4c9e8e49..798fe3a9004b778e69a2d137638d57ab8746f57c 100644
--- a/specifications/README.md
+++ b/specifications/README.md
@@ -81,3 +81,10 @@ SISO-REF-010 specifies numerical values and associated definitions for fields th
 [Operations Manual (OPMAN)](https://www.sisostds.org/DigitalLibrary.aspx?Command=Core_Download&EntryId=47284)
 
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+
+**6. SISO-STD-001-2015: Standard for Guidance, Rationale, and Interoperability Modalities (GRIM) for the Real-time Platform Reference Federation Object Model (RPR FOM)** <a href="https://www.sisostds.org/ProductsPublications/ReferenceDocuments.aspx" target="_blank"><img src="SisoLogo.jpg" width="314" align="right"/></a>
+* https://www.sisostds.org/ProductsPublications/Standards/SISOStandards.aspx (scroll down near bottom of page)
+SISO-STD-001-2015 encapsulates guidance in the use of the RPR FOM. It provides descriptions of FOM classes and data types and the relationship between Distributed Interactive Simulation (DIS) and the High Level Architecture (HLA)-based RPR FOM, as well as rules for accomplishing specific distributed simulation tasks.
+* Version 2.0 (10 Aug 2015)
+
+---