Luke, Non-maintained fittings are wired in a reasonably standard way, ie: Live/Neutral Pair as a radial (Earth obviously included!!)
Maintained fittings are wired with three core and earth, One core is a permanent live (Usually L1), one core is switched (Usually L2) and one core the neutral.
All types must include test switches (Key switch) and they should be as reasonably close to the fittings as possible, but usually one key switch per room/corridor/stairwell.
For the Inverter based Emergency firrings there is usually a central test switch which is used to simply kill the supply to the charger circuit.
As an example for use..
A light fitting in a room and forming part of the normal lighting circuit would be a maintained type of fitting as it would be switched on with all the usualy lighting, but would energise on the battery pack should the 230V permanent live fail.
A light fitting whose sole purpose is emergency illumination would be a Non-Maintained type, these are usually used over fire exits and on stairwell escape routes. Often they are Illuminated constantly, but several manufacturers also allow for an OFF state so they only illuminate on Power Failure. Depending on the building use, it is highly likely you would find both types in a given building, especially if it is publicly accessible , such as cinema's, Pubs, restaurants etc.
The Inverter type system is old hat now and very rarely installed, they are not very cost efficient in terms of installation and maintenance, but occassionaly they are still put in when the building has special requirements..usually Government ones..