optgroup> - OPTGROUP TAG IN HTML
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optgroup> | HTML | WebReference
Quick Tip: Don't Forget the “optgroup” Element
Html.optgroup lacks "label" attribute · Issue #136 · elm/html · GitHub
Select2 v4.0 make optgroups selectable - Stack Overflow
javascript - How to Dynamically Create <option> elements within a parent < optgroup> - Stack Overflow
OPTGROUP Tag in HTML || HTML Optgroup Tag
Grouping Form Elements in HTML: Combobox UI Control for Webpage.
Optgroup Tag (Form Tag) Example
How to specify a label for an optgroup tag in HTML5 ? - GeeksforGeeks
HTML <optgroup> Definition, Usage and Examples - Holistic SEO
html tutorial - <optgroup> Tag in HTML - html5 - html code - html form - In 30Sec by Microsoft Award MVP - | wikitechy
How to specify a label for an optgroup tag in HTML5 ? - GeeksforGeeks
Using option groups (<OPTGROUP>) in Forms 2.0 picklists — TEKNKL :: Blog
File:HTML-select-optgroup-example-gl.png - Wikimedia Commons
HTML Select, Option and Optgroup tags - Lena Design
Quick Tip: Don't Forget the “optgroup” Element
Styling single selection menu control option groups (optgroup elements) with CSS | 456 Berea Street
javascript - Bootstrap optgroup selection - Stack Overflow
