Using trimToDays-function in xpath to retrieve records

Hi all, I am trying to retrieve records from the database on a matching date.  To that end, I have removed the time component of both data&time fields using the trimToDays function.  However, it tell me that this function is unknown. See below.  Any pointers would be great!
1 answers

The trimtodays function is not avialable in the xpath queries. The available functions are described here:

Your query needs to be a bit more complex as you’ll need to take the time portion into account.

So create 2 variables marking the start and end of the day from the tradeleg attribute and compare by greater than and smaller than for the start and end respectively.