@Midnight Blues
Thanks. I think you are correct in assuming 'speedlimits_x' group should probably be 'x = last + 1').
From looking at the country_info.ini file it seems the speedlimits_x groups are purely sequential for each country, with speedlimits_1 normally being Coach and any others assigned sequentially but to no fixed vehicle type.
It is the next 2 blocks which are the problem. They seem to be hexadecimal numbers but converting then to actual numbers doesn't reveal any obvious logic.