I have looked at the data sheets for parts with RS232, ECL, PECL and MECL
buffers, and every one of them has one of the rail voltages connected to a
Ground (GND) data book name (signal_name).
Although the IBIS standard does allow the user to associate all of the
rail voltages with bus_labels on POWER pins, such a buffer is an unnatural
If we state that it is a given that every buffer has a Ground rail
connection, then we can state that every buffer has a well-defined
reference node for every other terminal measurement at the buffer.
I challenge anyone on this committee to find a part with an I/O buffer
that has no rail terminals that are Ground.