Some great info in your book, thanks.
I have discovered an error however:
If you define a Parameter as a Date or Date with Time and the parameter field is not populated then instead of the parameter value being NULL as stated access Web apps return the SQL Server default for an undefined date that being 1/1/1900 12:00:00am.

So the partial SQL string listed on page 254 of:
"... OR [pdatScheduleDateFrom] IS NULL...
will NEVER be true!

What suggestions do the authors have to better match an empty entry?

Perhaps:
OR [pdatScheduleDateFrom] ="1/1/1900 12:00:00am" ???

Thanks for sharing, Brian.

I just tested that and indeed a default value is set. I'm fairly sure that was not the case when we were writing the book. Yes, you could use "=#1900-01-01 00:00:00#".