CD4013B: power derating and TI nomenclature

I’m trying to understand the CD4013B data sheet and have a couple questions:

1. I’m struggling to find something in writing (webpage, data sheet, etc) that defines TI’s nomenclatures, such as the E in CD4013BE part number. Will you point me to such a resource? I’m trying to fully capture the differences between the CD4013BE and the CD4013BEE4.
2. The power derating info in the CD4013B datasheet on page 4, section 6.1…
   1. Is the max power dissipation both 500mW AND 200mW at 100°C? Will you help me understand this derating info?
   2. Does this part not derate to 0mW at 125°C? Because 200mW to 0mW from 100°C to 125°C doesn’t add up to the derating linearity of 12mW/°C in note 3 below the table in section 6.1. It adds up to 8mW/°C. Or does it derate at a rate of 12mW/°C, from 500mW at 100°C to 200mW at 125°C. That math adds up and makes sense to me.

Thanks in advance!