Why does SWbemServices.ExecQuery return more properties than requested?

I'm getting unexpected results from the below JScript code. The *Index* property is returned even though I've only requested *MACAddress*.


What's going on here?


**JScript:**

<!-- language: lang-js -->

var wmi, col, itr, obj;

wmi = GetObject('winmgmts:');
col = wmi.ExecQuery('SELECT MACAddress FROM Win32_NetworkAdapterConfiguration');
itr = new Enumerator(col);

for (; !itr.atEnd(); itr.moveNext()) {
obj = itr.item();
itr = new Enumerator(obj.Properties_)
for (; !itr.atEnd(); itr.moveNext()) {
obj = itr.item();
WSH.echo(obj.name)
}
}

**Output:**

Microsoft ® Windows Script Host Version 5.8
Copyright © Microsoft Corporation. All rights reserved.

Index
MACAddress

This behavior is normal, the WMI always returns (if is present) the key property (a property that uniquely identifies an instance of a class) and the others specified in the WQL sentence.