[EpiData-list] numerical to date chk?

Dear Epidata list, I am looking for a way to generate a date-variable from a numerical-variable.

i.e. I will type in the Danish central person registration number (10 digits where the 6 first digits are the birthday ddmmyy) I would like to automatically create a date variable from this - to calculate ages at later dates.

I have looked for a chk that would do it, but couldn't find any. Does anybody have a solution? (and sorry if this has been discussed before, I searched and couldn't find any relevant discussion threads)

thanks in advance, Drude Molbo, data admin dept. of social medicine, KU DK