TASCAM US1800 ASIO 1/L = 1
TASCAM US1800 ASIO 1/R = 2
TASCAM US1800 ASIO STEREO = 1&2

etc.

Thanks Beag, I didn't see that described anywhere in the manual, it's kind of a goofy way to identify the inputs. Why do they do it that way? Is that typical for a multi input interface?

I agree it's a goofy way to identify them and I don't know why it's done that way.  it has something to do with the way ASIO drivers are written and something to do with the way Sonar interprets the drivers and yes, for ASIO multiple input devices, this is typical.
 
(I don't have a Tascam US1800, but I knew the answer to your question because it's a typical question for first time multi-input ASIO users)

As usual...... Thanks for your help! Now I know it's working right also (-=

Is it possible to rename inputs in X2?

yes and no, hit "P" on the keyboard to bring up the preferences.  then on the left side you'll see the "friendly name" and on the right side is the "driver name"  if you double click on the friendly name it will allow you to change it to something more "friendly"

however, this only changes the primary name and doesn't allow you to change the individual channels like I'm sure you're wanting to do.

for example, on mine it's MOTU 1/2   is the current default "friendly" name.  and MOTU Audio ASIO Analog 1 is the "driver name."  so I can change the MOTU 1/2 to something else, but that's still not going to allow me to see separate channel names.

if I change it to MOTU 1

then what I would see when I select the channel in the track would be:
Left MOTU 1
Right MOTU 1
Stereo MOTU 1

so that didn't really help me at all.  I believe that cakewalk should rework this "feature" so that individual channels can be renamed, but that's not been their priority because it's been this way for several versions.

The L/R/Stereo is a common method on many recording devices.  I had a Focusrite Saffire Pro 40 and the inputs were identified the same as the Tascam.  Same way with my Roland Octa-Capture and MAudio Fastrack Ultra 8R.

After you get use to the naming convention its not a hassle.