postgresql - What does the values in column clazz (osm2po) mean?

I have a given table in postgreSQL with OSM data which is used for routing purposes in Java with PGRouting. There exist two columns which I don't understand. They belong to osm2po. They are labeled with "flags" and "clazz". I know, that flags describe the kind of road. It means, whether it is driveable by car, bike,... The problem now is, that I do not understand the meanings of the values in the column clazz. I just know that they also describe the road type. Can anybody explain, what the values like 12, 15, 31,... mean? Does a documentation exist where the meaning of the values is written down?

Answer

The file osm2po.config, which can be obtained from the downloads tab on the osm2po page, contains a table with four column, defined as:

1) concurrent order

2) class (1-127)

3) default speed in kmh

4) allowed transportation type (optional) - since v4.5.30

And here are some sample rows, which I think explain where the 12, 51, etc, you are seeing comes from (in the second column).

wtr.tag.highway.motorway =       1, 11, 120, car
wtr.tag.highway.motorway_link =  1, 12, 30,  car
wtr.tag.highway.service =        1, 51, 5,   car|bike
wtr.tag.highway.living_street =  1, 63, 7,   car|bike|foot  

It does say that the class can be in the range 1-127, and there are only 23 different values in that config table, so I trust that covers all the ones you are seeing?

Following comment from OP, here are the the official osm highway docs