ITSO on Prestige has finally made some progress. Weekly and monthly
seasons on Southern's Key card can now be purchased to Coulsdon South
and Purley at Southern TVMs, and the gatelines at these two have been
updated to read ITSO cards as well as Oyster cards. As usual, the TVMs
don't seem to read any other ITSO cards, even including other Key
cards.

Southern's TVMs outside London also offer the ability to load single
tickets starting at other stations, including those in other smartcard
schemes. I managed to add a CDR from Staines to Datchet and a single
from Mansfield to Mansfield Woodhouse to my Southern Key card. Whether
these etickets would be accepted for travel is an interesting
question..