Not sure how it works in Denmark, but in Sweden the life sentence is also usually refereed to as being "max 16 years", or some similar number between 10-16 years.

However that is not quite the whole story. In Sweden, a life sentence is a sentence with no upper bound on the time, if you were immortal, you would be there forever. But, usually you are considered rehabilitated after, say, 10-16 years, if you indeed show signs that you have rehabilitated. Then there is no need to keep you locked up.

The "max X years" is meant as the number for which it took the longest time for someone to be considered rehabilitated. In the Swedish sense of it, it is not a "magic" number, but a case-by-case number.

EDIT: the user "nl" quotes the wikipedia article for Denmark in another reply which indicates it is more or less the same.