Changing Characteristics and sold products

HI

I have created the following characteristic with the following values:

Week 1 - "No Selection", "Tue 26/03/2013 6pm-8pm" and "Wed 27/03/2013 2pm - 4pm".

Can I make changes to the characteristic without affecting existing variants that have been sold or bought by customers. That is if I change:

Tue 26/03/2013 6pm-8pm --> change to Tuesday 26/04/2013 6pm 8pm, will it update all previous variants sold with Tue 26/03/2013 6pm-8pm ?

thanks

Patrick