Now that it's 2018, there's less than 10 years remaining before HP's intrinsic for date handling on MPE/iX loses its senses. CALENDAR's upcoming problems have fixes. There's a DIY method that in-house application developers can use to make dates in 2028 read correctly, too.
The key to this DIY repair is to intercept a formatting intrinsic for CALENDAR.
CALENDAR returns two numbers: a "year" from 0 to 127 and a "day of year" from 1 to 366.
FMTCALENDAR takes those two numbers and turns it into a string like Monday, January 1, 1900. It takes the "year" and adds it to 1900 and displays that. "In a sense," explains Allegro's Steve Cooper, "that's where things 'go wrong'."
If one intercepts FMTCALENDAR and replaces it with their own routine, it can say if the "year" is 0 to 50, then add 2028 to it, otherwise, add 1900 as it always did. That would push the problem out another 50 years.
This interception task might be above your organization's pay grade. If that's true, there are 3000-focused companies that can help with that work. These kinds of repairs to applications are the beginning of life-extension for MPE/iX systems. There might be more to adjust, so it's a good idea to get some help while the community still has options for support.