2.2.32 [HTML] Section 16.4.1, The NOFRAMES element


The specification states:

 The NOFRAMES element specifies content that should be displayed only by user agents 
 that do not support frames or are configured not to display frames. User agents 
 that support frames must only display the contents of a NOFRAMES declaration when 
 configured not to display frames. User agents that do not support frames must 
 display the contents of NOFRAMES in any case.

All Document Modes (All Versions)

The content of the NOFRAMES element is ignored when a site is a member of the Restricted sites zone.