Which is right in web-design?

[Humza]

On drop down lists, etc. (pre-selected) is it:
selected="selected"
OR
selected="yes"
(I know in FF 3 and IE 7 they both work), but i mean to conform to the standards.

Thanks in advance
Made a simple document to test &:
nibinaearr: # Line 16, Column 17: "SELECTED" is not a member of a group specified for any attribute.

<option SELECTED>Colorado -- CO</option>

?
# Error Line 16, Column 17: XML Parsing Error: Specification mandate value for attribute SELECTED.

<option SELECTED>Colorado -- CO</option>

So glad i didn't waste my time searching that one.
MrKey: Thanks, i didn't think of that.
selected="yes" - Invalid
selected="selected" - valid

[mrkey!]

It depends.
You can validate your html/css at these addresses:
http://jigsaw.w3.org/css-validator/ - CSS
http://validator.w3.org/ - HTML
Of course, there's no need to validate PHPs

[nibinaearr]

It's like this:

<option value= "" SELECTED>my text</selected>

You could have just look this up on Google which would have saved you asking the question.