VFP Data Engine allow a null expression into the where condition,
and this is a bug on the VFP Parser:

Run this:

CLEAR
CREATE CURSOR _TABLE (F1 L NULL)

SELECT 2 FROM _TABLE T1 WHERE ! .NULL. INTO ARRAY zz   && this skip the row
SELECT 2 FROM _TABLE T1 WHERE .NULL. INTO ARRAY zz     && this fire a syntax error