[1] [MS-WMSP]: proxy-public ( 版) <https://msdn.microsoft.com/en-us/library/cc251239.aspx>
This directive specifies that if the cache is a proxy server, the content MAY be shared with other clients or other proxy servers. If the cache is a proxy server, this directive overrides the private (section 2.2.1.1.4) directive.<6>