2.1.920 Part 1 Section 18.17.7.76, DATEVALUE

a.   The standard states the function computes the serial value of the date and/or time represented by the string date-time-string, taking into account the current date base value.

In Office, the function computes the serial value of the date represented by the string date-time-string, taking into account the current date base value.

b.   The standard does not specify what happens when the date-time-string argument contains both a date and time part.

Office truncates the time portion of the date-time-string argument, or returns 0 for time only values of date-time-string argument.