The VFP 9 Help says the following re 9.0 SQL enhancements:

A SELECT … DISTINCT … ORDER BY command will generate an error if the specified ORDER BY field is not in the SELECT field list.

However the followig sql statement generates a "SQL: Order By clause is invalid" error:

SELECT DISTINCT (Sales / 10) as sales FROM saleshist INTO CURSOR test ORDER BY sales

Setting EngineBehavior 80 gets rid of the error condition.

Is is a Bug ?

A work around is:

SELECT DISTINCT (Sales / 10) as Sales1 FROM saleshist INTO CURSOR test ORDER BY sales1

but the workaround is a pain.