This conditional S-Tag will determine if the logged-in user is a sustaining donor.

[[?xxCurrent Sustaining Donorxx::xx[[S1:sustained_status]]xx::
This person is currently a sustaining Donor
::
[[?xxFormer Sustaining Donorxx::xx[[S1:sustained_status]]xx::
This person USED TO be a sustaining Donor
::
[[?xxNever a Sustaining Donorxx::xx[[S1:sustained_status]]xx::
This person has NEVER be a sustaining Donor
::
I have no idea if this person has sustaining donated.
]]
]]
]]