optgroup

Element Information

Model

option+
Children: option

Attributes

QName Type Fixed Default Use Inheritable Annotation
class xs:string optional
dir restriction of xs:NMTOKEN optional
disabled restriction of xs:NMTOKEN optional
id xs:ID optional
label Text required
lang LanguageCode optional
onclick Script optional
ondblclick Script optional
onkeydown Script optional
onkeypress Script optional
onkeyup Script optional
onmousedown Script optional
onmousemove Script optional
onmouseout Script optional
onmouseover Script optional
onmouseup Script optional
style CDATA optional
title xs:string optional
xml:lang union of(xs:language, restriction of xs:string) optional 
Attempting to install the relevant ISO 2- and 3-letter
         codes as the enumerated possible values is probably never
         going to be a realistic possibility.  See
         RFC 3066 at http://www.ietf.org/rfc/rfc3066.txt and the IANA registry
         at http://www.iana.org/assignments/lang-tag-apps.htm for
         further information.

         The union allows for the 'un-declaration' of xml:lang with
         the empty string.
xml:space restriction of xs:NCName preserve optional

Source 

<xs:element name="optgroup" type="xhtml.optgroup.type"/>

Sample