ttLeftSquareBrace throws exception?

[Woodzzter]

Using Zeos 6.1.5 and another 3rd Party GUI DB Controls library, we are trying to calling TZAbstractRODataset.SetFilterText with the value

"([id]) IS NOT NULL)")

This throws an exception in the TZExpression.SyntaxAnalyse6 function when trying to evaluate the ttLeftSquareBrace character.

At this point the folowing function local variables are set:

Primitive := ttLeftSquareBrace
NextToken := ttVariable

The value for Primitive fails all comparisons and drops through to

raise TZParseError.Create(SSyntaxError);

A quick search through all the Zeos source reveals that although the ttLeftSquareBrace is enumerated, it is not actually referenced anywhere.

Am I missing something here or are square braces not catered for when parsing expressions in Zeos 6.1.5?