2.2.4 [W3C-P3P1.0] Section 2.3.4, Forms and Related Mechanisms
The specification states:
User agents SHOULD NOT attempt to issue a HEAD request to an action URI if the relevant methods specified in the form's method attribute have been properly predeclared in the page's policy reference file.
All Document Modes (All Versions)
HEAD requests are never issued regardless of the methods that have been predeclared in the policy reference file of the webpage.