Here are the two combinations that fail your rule for this specific case:

a, b, c   a or b and c
T, F, F   T
T, T, F   T

The priority/precedence of logical operators is similar to the one applied to arithmetic operators, using the following equiv:

NOT - ^ -- Maximum priority
AND - *
OR - + -- Minimum priority

Vlad

>Yes they are evaluate from left to right as in;
>
>a=.T.
>b = .F.
>c = .T.
>
>?a or b and c && .T.
>
>a = .f.
>
>?a or b and c && .F.
>
>b = .t.
>?a or b and c && .T.