every time I have to markup date input-fields in a form, I'm faced with the same question: "What's the best way to bind a label to a group of select-elements?"

'Cause basically you have this:

HTML Code:
<label>Your date of birth:</label>
<label for="month">Month:</label>
<select id="month"><!-- 12 Option-elements here please --></select>
<label for="day">Day:</label>
<select id="day"><!-- lots of Option-element go here --></select>
<label for="year">Year:</label>
<select id="year"><!-- lots of Option-elements go here --></select>
Most of the time I hide the month-day-year labels using CSS, and only show the first label, but what should go in the "for"-attribute of that label?
What's semantic and accessible?