We all know how to form a checkbox input in HTML:
<input name="checkbox_name" id="checkbox_id" type="checkbox">What I don't know -- what's the technically correct value for a checked checkbox? I've seen these all work:
<input name="checkbox_name" id="checkbox_id" type="checkbox" checked><input name="checkbox_name" id="checkbox_id" type="checkbox" checked="on"><input name="checkbox_name" id="checkbox_id" type="checkbox" checked="yes"><input name="checkbox_name" id="checkbox_id" type="checkbox" checked="checked"><input name="checkbox_name" id="checkbox_id" type="checkbox" checked="true">Is the answer that it doesn't matter? I see no evidence for the answer marked as correct here from the spec itself:
Checkboxes (and radio buttons) are on/off switches that may be toggled by the user. A switch is "on" when the control element's checked attribute is set. When a form is submitted, only "on" checkbox controls can become successful. Several checkboxes in a form may share the same control name. Thus, for example, checkboxes allow users to select several values for the same property. The INPUT element is used to create a checkbox control.
What would a spec writer say is the correct answer? Please provide evidence-based answers.