Doors can be restricted to certain access levels. The engine knows about 32 access levels (0..31).
The names of the access levels are stored as texts in resource 0x0879. Per access level there
are two text strings, so 64 in total. The first string is the short name, for example STD and the second the long
name, Standard.
The first level (0) with name None is not checked. Doors with level 0 immediately open.