Birthday calendar, initial event year => calculate persons age

Wasn't able to find a method to read the birthday instead of the calendar event year?

I compiled a quite customized, really nice calendar.

What i'd like to show, is the persons age.

With ci(start..) i get the event year (i.e. obviously this year ;-) ), not the initial (birthday) year.

As I'm quite new, i might have overlooked similar earlier posts.

BTW. great tools, compliment to the designer!

Kind regards,