So, I have to make sure the shop will use the 236.10 ATF. Is this 236.10 the name of the fluid?
What is the current ATF used by the dealer?
Absolutely, and that's one of several questions you can use for vetting the shop. I chose mine by surfing initially, whittled that list down, made some phone calls and streamlined it more, and then I started visiting the few that were still viable options. Sometimes I'd just ask, specifically, what fluid they would use, and in some cases I'd ask if they would use Mobil1 Synthetic ATF. (This fluid is okay for older 4 speeds, but not the five, it meets MB specs 236.1 through 236.9 IIRC.) More than one had it all correct and I chose the one that had the highest percentage of MBs in the shop -- happily it was also the closest to where I live.
236.10 is the official MB specification for the original fluid for the five-speed. Fuchs still makes it; MB could get it if they wanted but they like things streamlined (apparently).
The fluid now at the dealerships is the 236.14 fluid, which replaced the 236.12 fluid that originated with the 7-speed. The 236.14 seems to work fine in the 7-speed, but there are far too many stories of problems with it in the 5-speed. They began phasing out stock of the 236.10 fluid a couple of years ago.
If you'd like to learn a great deal more about your transmission (nothing really too technical), drift down to the sedans section, click on the W210 section, then at the top there are help/diy sticky threads. Choose the driveline one, and in there is an outstanding 722.6xx FAQ thread...722.6xx includes all of the flavors of the five-speed MB transmission, including yours. Great info and links to more.