Airport Grass in FS9

[Springer6]

Does anyone know which textures are used for the background ground polygons in FS9 airports ( European)?

They seem to be "grass", "grass_fa", "grass_wi", "grass_sp", "grass_hw" . For summer, fall (autumn),winter , spring and winter wonderand (snow).

Can I just specify these textures in FSSC when designing an airport ?

Can I get them to change with the season as the stock airfields do ?