Can you please tell me whether I'm interpreting the following correctly?

Section 3.6.26 of the Quality Data Model, Version 4.1 document (http://www.healthit.gov/sites/default/files/qdm_4_1.pdf) says:

"It is important to note that whenever a temporal operator compares a
null (i.e., missing) date/time, it will always evaluate to false. For
example, Ends Before Start Of returns false if the left-hand side
event has a missing end date/time or the right-hand side event has a
missing start date/time. Consult the definition of each temporal
operator to determine which date/times are required."

This seems to imply that there are some pairs of time intervals for which "A Starts After Start Of B" evaluates to true and "A Ends After Start Of B" evaluates to false (specifically, any pair where the start time of A occurs after the start time of B, and the end time of A is null). Is this correct? It seems a little counterintuitive.