Validator: there is no attribute "onClick" /// Wie sonst?

[Jeena Paradies]

Hallo,

Irgendwie komme ich nicht so richtig mit der Meldung des Validators klar:

Line 78, column 18: there is no attribute "onClick" (explain...).
     <input onClick="document.getElementById('gruss').style.display='block'; docum
                    ^
[...]
  78: <input onClick="document.getElementById('gruss').style.display='block'; document.getElementById('gruss').style.visibility='visible'" class="radio" type="radio" name="begrusung" value="an" checked='checked' />an
  79: <input onClick="document.getElementById('gruss').style.visibility='hidden'" class="radio" type="radio" name="begrusung" value="aus"  />aus
[...]

Was ist da falsch?

Grüße
Jeena Paradies