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According to Wikipedia and Owasp, the only defined value, "nosniff", prevents Internet Explorer from MIME-sniffing a response away from the declared content-type. This also applies to Google Chrome, when downloading extensions.
X-Powered-By
It's recommended to not use the X-Powered-By header.
Tomcat documentation: <<The xpoweredBy attribute controls whether or not the X-Powered-By HTTP header is sent with each request. If sent, the value of the header contains the Servlet and JSP specification versions, the full Tomcat version (e.g. Apache Tomcat/7.0.0), the name of the JVM vendor and the version of the JVM. This header is disabled by default. This header can provide useful information to both legitimate clients and attackers.>>
OFBiz users can decide to change this parameter if they want