Леголегс пишет:
document.getElementById("ИД"
полностью заменяет document.all

CODE:
<form id=f2>
<a id=a>a2</a><input id=i>
</form>
<form id=f3>
<a id=a>a3</a><input id=i>
</form>
<a onMouseOver="document.body.innerHTML+=document.forms['f2'].getElementById('a').innerHTML">---------</a>
<a onMouseOver="document.body.innerHTML+=document.forms['f2'].all['a'].innerHTML">---------</a>
<form id=f2>
<a id=a>a2</a><input id=i>
</form>
<form id=f3>
<a id=a>a3</a><input id=i>
</form>
<a onMouseOver="document.body.innerHTML+=document.forms['f2'].getElementById('a').innerHTML">---------</a>
<a onMouseOver="document.body.innerHTML+=document.forms['f2'].all['a'].innerHTML">---------</a>