A disabled <command> element:
The disabled attribute is currently not supported in any of the major browsers.
Note: Internet Explorer 9 (not earlier or later versions), supports the disabled attribute.
The disabled attribute is a boolean attribute.
When present, it specifies that the command element should be disabled.
The <command> tag is new in HTML5.
In XHTML, attribute minimization is forbidden, and the disabled attribute must be defined as <command disabled="disabled">.