[aprssig] on a multi-TNC digipeater, which callsign should be traced?

[John Langner WB2OSZ]

>> Some other implementations always insert, and never substitute, 
>> which can cause confusion about the path taken.

> Hmm, what sort of confusion would it create?

Suppose you receive a packet with a path like this:

W1AAA>APRS,W9ZZZ,WIDE2*

Are you hearing W9ZZZ or another station that didn't implement tracing?

You don't know because different implementations behave differently.

The User Guide section referenced earlier has an explanation and examples
too long to copy here.