Ø @FALSE -
The logical value 0.
Ø @FILEEXISTS(S) -
1 if file S can be opened for reading; otherwise 0.
Ø @IF(X, T, F) -
The value of T if X evaluates to on-zero, or F if X evaluates to zero.
Ø @ISERROR(X) -
Returns 1 if X ``contains"" an error, otherwise 0.
Ø @ISNUMBER(X) -
1 if X is a numeric value; otherwise 0.
Ø @ISSTRING(X) -
1 if X is a string value; otherwise 0.
Ø @TRUE -
The logical value 1.