Indeed, thanks for Keil and their chip database.

But looking at Atmel chips I may say that not all derivatives are included. From other side, many of these presented, are not filled with parameters. For example, AT89C51RD2 is indicated with no flash, ram, timers etc. Nevertheless even Keil site has provided correct information about this chip, look at: http://www.keil.com/dd/chip/3597.htm
And there are alot of such "empty" lines in chip database: AT89C51CC03, AT89C51ED2, AT89C51ID2, etc.
By the way, if Keil does not support some derivatives, it does not mean that they are not present in the whole. For example, there is official datasheets on Atmel site about AT89S8253, AT89C51AC3, AT89C51SND2C; SiLabs produces C8051F130-133, C8051F312-315 etc.

More, some chips which are included into the base are obsolette and market as "do not use in new design" by their vendors (for example, AT89C51, C52 etc). Here is an idea: mark new chips (let say, one-two months after they have been announced) with flag "new" and obsolette ones with "dead" or somehow else.

Thanks,
Oleg