a0d929ca_WSRP_v2_0_Specification__Statement_text
[#] CS146 [Section] 9.2.1.6 [Statement text] 
The wsrp-windowState portlet URL parameter MAY be used whenever the wsrp-urlType portlet URL parameter has a value of "blockingAction" or "render".
WSRP v2.0 Specification
Statement text