<OPTGROUP> | NN n/a IE n/a HTML 4
<OPTGROUP>...</OPTGROUP> | End Tag: Required
The OPTGROUP element offers the possibility that future browsers will provide a hierarchical SELECT element. An OPTGROUP element represents a container of OPTION elements. The LABEL attribute is the text that would appear in the main SELECT element listing, with nested OPTION elements cascading off the side when the OPTGROUP element is highlighted.
Example
    <SELECT NAME="carCos">
        <OPTGROUP LABEL="American">
            <OPTION VALUE="General Motors">General Motors
            <OPTION VALUE="Ford">Ford Motor Company
            <OPTION VALUE="Chrysler">Chrysler Corporation
        </OPTGROUP>
        <OPTGROUP LABEL="Japanese">
            <OPTION VALUE="Toyota">Toyota
            <OPTION VALUE="Honda">Honda
            <OPTION VALUE="Nissan">Nissan
        </OPTGROUP>
    </SELECT>

DISABLED | NN n/a IE n/a HTML 4
DISABLED | Optional
The presence of this attribute disables the OPTGROUP element and its nested OPTION elements.
Example
    <OPTGROUP LABEL="Engineering" DISABLED>
Value The presence of this attribute sets its value to true.
Default | false

LABEL | NN n/a IE n/a HTML 4
LABEL="labelText" | Required
The text of the SELECT element entry for the OPTGROUP is defined by the LABEL attribute. This is plain text, not HTML.
Example
    <OPTGROUP LABEL="Engineering" DISABLED>
Value Any string of characters. The string must be inside a matching pair of (single or double) quotation marks.
Default | None.