a0d929ca_WSRP_v2_0_Specification__Statement_text
[#] CS142 [Section] 9.2.1.4 [Statement text] 
The value of this portlet URL parameter defines the interaction state the Consumer MUST send to the Producer when the URL is activated. If this parameter is missing, the Consumer MUST NOT supply the interactionState field of the InteractionParams structure.
WSRP v2.0 Specification
Statement text