Genmeshes are used to reduce the amount of geometry CS will handle. You can 
  define a "factory" object (example: a stone) and then copy it in several places 
  of the level. If it's a genmesh the copies will be exported with the reference 
  to the factory, plus their position and rotation, all the geometry will be identical 
  to the "factory" object. This saves a lot of memory. Please note that genmeshes 
  can have just one material per object. You can have one material (e.g. stone1.gif) 
  on the factory, a different one on a certain instance (e.g. stone2.gif), and 
  so on. You cannot have two materials (e.g. column_top.gif and column_body.gif).
To have genmeshes working you must follow carefully these procedures.
Create a valid factory:
  - Define a valid name for factory 
    
      - name it with a starting "_g_" prefix
- name it with a unique identifier that will be used on copies. eg.: "_g_stonebig"
- add a "_0" suffix to the end of the name to tell the exporter that this 
        is a factory.
- A valid factory name is: "_g_stonebig_0". Underscores should be in the 
        right quantity: "_g_stone_big_0" is invalid and this will not be 
        considered a factory.
 
- Reset the factory 
    
      - Move the factory object to 0,0,0. This will be used as a reference for 
        the position of all other instances
- Select the object, go to Hierarchy, click on Affect Object Only, and 
        then "Align to World", "Center to Pivot"
- Click on Affect Pivot Only, and then "Align to World"
 
Create a valid instance:
  - Define a valid name for instance 
    
      - name it with a starting "_g_" prefix
- use the same unique indentifier of the factory (I mean the central part 
        of the name. e.g. "stonebig")
- add a unique suffix at the end of the name: eg.: "_g_stonebig_01"
 
- Reset the instances 
    - NEVER create an instance by mirroring the factory. Mirror function mess 
      up the pivot, so we have no way to have it oriented correctly when exported. 
      To create an instance copy the factory object and then rotated it, move 
      it as you wish.
- Select the object, go to Hierarchy, click on Affect Object Only, and then 
      "Center to Pivot"
- Click on Affect Pivot Only, and then "Align to object"
Please note that the factory is NOT exported in the scene, so it will be invisible 
  in CS.
All genmeshes have the tiling mixmode.
Shadows: genmeshes can have the same settings Objects have for shadows 
  (see Object Properties).
Trasparency: if the object has a transparent texture you have two options:
  1) if the object is made of just one plane you can just add the property transparent 
  on the factory object (see Object Properties)
2) if the object is made of many planes, some of which can be seen as overlapping 
  by the player (like two parallel planes one after the other), then you must 
  add the transparentmultiple property on the factory object (see Object 
  Properties)
 
Thingmeshes are used to reduce the amount of geometry CS will handle. You can 
  define a "factory" object (example: a house) and then copy it in several 
  places of the level. If it's a thingmesh the copies will have only the location, 
  rotation and texture associated, all the geometry will be identical to the "factory" 
  object. This saves a lot of memory. The difference with genmeshes is that thingmesh 
  instances can have a different texture from the factory, that thingmesh support 
  multiple textures and that those "can receive light (check with Jorrit)".
To have thingmeshes working you must follow carefully these procedures.
Create a valid factory:
  - Define a valid name for factory 
    
      - name it with a starting "_f_" prefix
- name it with a unique identifier that will be used on copies. eg.: "_g_house"
- add a "_0" suffix to the end of the name to tell the exporter that this 
        is a factory.
- A valid factory name is: "_f_house_0". Underscores should be in the 
        right quantity: "_f_house_big_0" is invalid and this will not be 
        considered a factory.
 
- Reset the factory 
    
      - Move the factory object to 0,0,0. This will be used as a reference for 
        the position of all other instances
- Select the object, go to Hierarchy, click on Affect Object Only, and 
        then "Align to World", "Center to Pivot"
- Click on Affect Pivot Only, and then "Align to World"
 
Please note that the factory is NOT exported in the scene, so it will be invisible 
  in CS.
Create a valid instance:
  - Define a valid name for instance 
    
      - name it with a starting "_f_" prefix
- use the same unique indentifier of the factory (I mean the central part 
        of the name. e.g. "house")
- add a unique suffix at the end of the name: eg.: "_f_house_01"
 
- Reset the instances 
    - NEVER create an instance by mirroring the factory. Mirror function mess 
      up the pivot, so we have no way to have it oriented correctly when exported. 
      To create an instance copy the factory object and then rotated it, move 
      it as you wish.
- Select the object, go to Hierarchy, click on Affect Object Only, and then 
      "Center to Pivot"
- Click on Affect Pivot Only, and then "Align to object"
Trasparency: if the object has a trasparent texture you should set a 
  property on the factory object (see Object Properties).
 
Next: Lights