The way I heard it from a reliable source is that the majority of layoffs will occur on Tuesday Feb 13th, and completing on Thur 15th. On Friday 16th, it will be a half day for all those who have not been let go. Those that have been let go will be given the opportunity to go back in the respective buildings, with an escort, and collect their personal belongings from their desks! Though, I must admit, I have never heard of being laid off and then been allowed back into the building under any circumstances but who knows?
The actual details of the terminations will be based on performance, and the '70' rule i.e.: years with the company plus your age, if it adds up to 70, show's over!