As I understand it, the 5V pull-up circuit is included in the EM-2 for the normal temps, but these aux channels can be used for other things.  Some of those other uses wouldn't work with a "normal" temp input circuit, so he made these inputs in a more generic way, so you could add the 5V pull-up externally, or not, depending on your needs

This looks like it is a simple voltage divider in which case the resistor values shouldn't matter much so long as the 2 resistors are within a few of ohms of each other.

        Or is there something I'm overlooking? The reason I ask is that 200ohms is not a standard resistor value (so I don't have any in my parts box), so it doesn't seem likely that Tracy would chose that value for a simple voltage divider, unless there is another reason.

S. Todd Bartrim
Turbo 13B
RX-9endurance
C-FSTB
http://www3.telus.net/haywire/RV-9/C-FSTB.htm

        "Imagination is more important than knowledge"
                                        -Albert Einstein