Thanks for enlightenment Joe, I know that there are some limitation with os module, that is why I said "more" error-proof and not "absolutely" error proof.
Most of the time I would use: >>> os.path.join("c", "Desktop", "Users", "jo", "mydatas") 'c\\Desktop\\Users\\jo\\mydatas' As far as possible I avoid using seps , what is the point of using os if you want harcoded abs paths. For that you can simply do a string concatenation. Also if you let your paths be decided procdurally, you would not end up having to write the sep yourself. Like in the example I write fileName = os.path.basename(filePath) then I do not care what separator is in fileName and it works perfectly (if I may) with oSource.Filename.value = os.path.join("Pictures", fileName) so in this case the code I wrote should work on os, win and linux. For the point in case softimage's BuildPath method can also be used. But again, nothing is perfect and I always follow "the-perfect-code-is-the-code-that-works" policy ! ;)