Specific names for plpgsql variable-resolution control options?

I believe we had consensus that plpgsql should offer the following three
behaviors when a name in a SQL query could refer to either a plpgsql
variable or a column from a table of the query:
* prefer the plpgsql variable (plpgsql's historical behavior)
* prefer the table column (Oracle-compatible)
* throw error for the ambiguity (to become the factory default)
and that we wanted a way for users to select one of these behaviors at the
per-function level, plus provide a SUSET GUC to determine the default
behavior when there is not a specification in the function text.

What we did not have was any concrete suggestions for the name or
values of the GUC, nor for the exact per-function syntax beyond the
thought that it could look something like the existing '#option dump'
modifier.

The code is now there and ready to go, so I need a decision on these
user-visible names in order to proceed. Anyone have ideas?

regards, tom lane