Jim,

>When complaining that property references don't work in a VFP SQL statement many people have told me (possibly even you) that it is because its SQL essentially runs 'outside the environment'.

What I've said in the past is that the commands run outside the scope of the form which makes access to their properties unavailable.

>I'd also say that the existence of SET ENGINEBEHAVIOR - which is documented as only affecting VFP SQL - also suggests isolation.

And there are NOOPTIMIZE clauses littered around on Xbase commands. Which suggests shared sharing.

>So, while nodody participating may know the correct answer, the observation that they are different is a logical one.

So no, we can't say exactly what is used where. What I think we can say is that the Rushmore engine is used by he SQL engine and the Xbase engine as VFP sees fit.