a0d929ca_WSRP_v2_0_Specification__Statement_text
[#] CS129 [Section] 9.2 [Statement text] 
If a Portlet is unable to completely write the portlet URLs for its markup, it MUST set the requiresUrlRewriting flag in the returned MarkupContext structure to “true”.
WSRP v2.0 Specification
Statement text