Many systems have their own formats for specifying the time data type. For example, you may support a format of the type: time between 'now' and 'now-2hr'. This allows the end user to specify time in a very flexible way. The OpenAccess SDK SQL engine easily supports this by letting you handle this expression. You decide if the rows you return have time data between now and now-2hr. In this case the OpenAccess SDK SQL engine will not attempt to evaluate this expression.