Hi Lane,
Considering the fact that TC utilizes standard VBScript library provided by the OS, I think that everything applicable for VBScript is relevant for TC as well.
Besides that, several times I've met with the situation when undeclared variable (quite often it was just a typo of the real variable intended to be used) was used in the script code and some time was spent for debugging to figure out why the variable is empty but do not contain expected value. Considering that test code is quite rarely requires 'near real-time performance', my opinion is that explicit declaration of the variable is preferred coding practice.
