Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.
Note: This property has been declared as deprecated by the W3C technical recommendation for HTML 4.01 in favor of use of the DTD for obtaining version information for a document.
Returns version information about the document type definition (DTD) of a document. While this property is recognized by Mozilla, the return value for this property is always an empty string.