To get the MAC id from the Ethernet card of the computer, use the GetEthernetAddress function.
If your Computer does not have an Ethernet card then a empty string will be returned.
Notes:
Retrieving information for multiple Ethernet cards is currently only supported on Windows x86, so only iID = 0 will work on MacOS.
It was decided not to develop this function further because REALbasic now has this functionality built in, because of that then there is no Linux implementation of this function.
The REALbasic built in function for this is:
System.GetNetworkInterface(0).MACAddress