From the next development release scenProc has a new feature, it is now possible to get auto completion of possible attributes and their values. All you have to do is scan the file you will be processing by pressing the “Scan attributes” button. Be aware that this might take a while for big files.
After that you will see that the auto completion when constructing a filter also shows the attributes and their possible values (as found in the OSM or Shapefile). This makes it a lot easier to construct the filters. And it is also a great way to explore which possible values there are for you to use.
Below is a quite video I made to demonstrate the feature.