# notice __FILE__ is always the same for 1.10 and 1.11/1.12

#ifver WESNOTH_VERSION >= 1.11.0
#define MAP __FILE__
    [map]
        data="{~add-ons/Terrible_Campaign/maps/{__FILE__}}"
    [/map]
#enddef
#else
#define MAP __FILE__
    map_data="{~add-ons/Terrible_Campaign/maps/{__FILE__}}"
#enddef
#endif

# ...

[scenario]
    id=01_Epic_Fail
    {MAP 01_Epic_Fail.map}
    # ...
[/scenario]