adding html attributes without a value using .net -

i want add multiple attribute select in .net. have done this:

if multiselect   drpselect.attributes.add("multiple", "true") end if 

though strictly speaking html should multiple.

for "boolean" html attributes (the ones should consist of name without value, required or multiple) accepted alternative use name="name", multiple="multiple".

in case should code

drpselect.attributes.add("multiple", "multiple") 

see w3c:

boolean attributes may legally take single value: name of attribute itself.