The function "dpTypeExists" is defined in the "wizardFramework.ctl".
I just installed 3.18 P017 and it is still there. It was already like this in P013.Not sure about older versions.
The wizardFramework is not automatically loaded in for the CONTROL Manager. But this has not changed between the versions.
You could just copy the function from there and make it available in your project.
Alright, on older version I didn't include the library and it worked so I guess this library is not imported by default from P017.
Thanks for the answer !