diff --git a/xyz/openbmc_project/State/README.md b/xyz/openbmc_project/State/README.md
index 0f59607..8bbf447 100644
--- a/xyz/openbmc_project/State/README.md
+++ b/xyz/openbmc_project/State/README.md
@@ -56,6 +56,18 @@
 The *Chassis* would provide interfaces at
 `/xyz/openbmc_project/state/chassis<instance>`
 
+### *Chassis System*
+This is an instance under *Chassis* and provide interface at
+`/xyz/openbmc_project/state/chassis_system<instance>`
+
+Instance 0 (chassis_system0) will be treated as a complete chassis system
+which will include BMC, host and chassis. This will support hard power
+cycle of complete system.
+
+In multi-host or multi-chassis system, instance number can be used from
+1-N, as 0 is reserved for complete system. In multi chassis system this
+can be named as chassis_system1 to chassis_systemN
+
 ## BMC to Host to Chassis Mapping
 
 In the future, OpenBMC will provide an association API, which allows one