1) The PathLAN software Y2K Bug The PathLAN software in use at Sheffield was derived from a standalone PC package. The specific area which failed was a date calculation module which extracted date information from strings to calculate maternal age at EDD. Date information was stored as a 10 character string:dd/mm/yyyyspecific items of information were extracted using a ‘Move’ command from either the Birthdate field or the Cldate [Collection date] field. Assuming a birth date of 12/04/1960 and a collection date of 11/03/2000, the original lines read and would have extracted the following:Move Birthdate[4,2] to #N0extracts 04Move Birthdate[9,2] to #N1extracts 60Move CLdate[4,2] to #N2extracts 03Move CLdate[9,2] to #N3extracts 00And the corrected lines read and extract:Move Birthdate[4,2] to #N0extracts 04Move Birthdate[7,4] to #N1extracts 1960Move CLdate[4,2] to #N2extracts 03Move CLdate[7,4] to #N3extracts 2000The values are converted into a number of weeks by multiplying the year figure by 52 and the month figure by 4. The ‘Birth weeks’ are subtracted from the ‘collection weeks’, 40 – gestation period is added to arrive at a number of weeks to expected date of delivery which is the divided by 52 to arrive at an age in years [as a decimal number]. As a date calculating routine, this is a very poor routine. Firstly, it ignores day of birth so a woman born on the first day of the month gets the same age at EDD as one born on the last day of the month. I suggest that even though the calculator has been used for years and that the Y2K error has been ‘solved’, a date calculation routine that actually calculates dates properly rather than making grossly inaccurate calculations should be used instead. An example that could be used is shown later in this report.A further problem with the date calculation routine is the lack of any error trapping routine. In my software (Downcalc), a...
