charset character_set Specifies the character encoding for the HTML document
content text Gives the value associated with the http-equiv or name attribute
http-equiv content-type
default-style
refresh Provides an HTTP header for the information/value of the content attribute
name application-name
author
description
generator
keywords Specifies a name for the metadata
scheme format/URI Not supported in HTML5.
Specifies a scheme to be used to interpret the value of the content attribute