I've seen the three implementations of pre-selecting a checkbox. I started off using checked=checked because I thought it was the proper way (never did like the checked=yes however). I am thinking of changing to checked=true as it seems more readable and is easier to code the JavaScript. Note that this same question applies to other attributes such as disabled=disabled versus disabled=true. As long as I am consistent, is using true the preferred approach? Thank you

<input type=checkbox checked=checked value=123 name=howdy />

<input type=checkbox checked=true    value=123 name=howdy />

<input type=checkbox checked=yes     value=123 name=howdy />