(a) Except as provided by Subsection (b), if the minimum number of signatures required for a petition is determined by a computation applied to the number of registered voters of a particular territory, voters whose names appear on the list of registered voters with the notation "S", or a similar notation, shall be excluded from the computation.
(b) The signature of a voter whose name appears on the list of registered voters with the notation "S", or a similar notation, is considered valid if the voter:
(1) is otherwise eligible to vote in the territory; and
(2) provides a residence address located in the territory.