Wouldn't it be useful to mark SQL bind variables with a placeholder character in PL/SQL too ?
SQL statements could be run/tested easier in IDE's as Toad or SQLDeveloper by simply providing the bind values instead of having to modify the statement before.
Additionally this would prevent code from failing silently after adding SQL column name PL/SQL variable name conflicts as
DECLARE
status1 EVEN_MORE_IMPORTANT.STATUS%TYPE := 1;
status2 EVEN_MORE_IMPORTANT.STATUS%TYPE := 2;
SELECT .. FROM ...EVEN_MORE_IMPORTANT... WHERE .. STATUS = status1..;
-- will fail gleefully years later
-- when adding the famous status1:
-- ALTER TABLE EVEN_MORE_IMPORTANT ADD (status1 NUMBER);
-- so a clear bind variable identification would be more readable and secure
-- SELECT .. FROM ...EVEN_MORE_IMPORTANT... WHERE .. STATUS = :status1..;