Multiple Submit Buttons: Can I Control Which Values Will Be Submited?

I have a complicated page with several submit buttons. I don't want to
create multiple forms because much of the input is shared and the code
is getting very ugly. However I would like to determine which values
will be submited.

Here is a simplified example that may better illustrate my question.
Or maybe there is a better approach...

<SCRIPT language="JavaScript">
function submitform1()
{
document.myform.submit();
}

function submitform2()
{
// logic to submit only name parameter
document.myform.submit();
}

function submitform3()
{
// logic to submit only address parameter
document.myform.submit();
}
</SCRIPT>

<form name="myform" action="#">
<TABLE>
<TR><TD>Name</TD><TD><input type='text' name='Name'></TD></TR>
<TR><TD>Address</TD><TD><input type='text' name='Address'></TD></TR>
<TR><TD>Phone</TD><TD><input type='text' name='Phone'></TD></TR>
<TR><TD></TD><td><input type="button" onClick="submitform1()"
value="submit all variables"> </TD></TR>
<TR><TD></TD><td><input type="button" onClick="submitform2()"
value="submit just name"> </TD></TR>
<TR><TD></TD><td><input type="button" onClick="submitform3()"
value="submit just address"> </TD></TR>
</TABLE>
</form>