Changing the retention period in the archive copy group, which effect has that?

Hi,
I have really searched the forum for an answer on my question:

A user of TSM wants to change the retention period in a management class for his archived data from 3 to 5 years. Which effect has that on the data that is already archived with the retention period of 3 years?

Will only the new data which is archived after this 'date of changing' get the retention period of 5 years?

Thank you for your answer!