TDI numbers on the Etrac and the Explorer XS

[sandnsea49]

I have an old Explorer XS as well as the Etrac. On the Etrac I understand the ferrous and conductive numbers and how we are not supposed to pay all that much attention to the ferrous numbers but the conductive ones. Now on the old XS I used to use the cursor to figure out my finds. My question is if the ferrous numbers are not that important then why not use the condunctive numbers on the XS instead of the cursor?