Available in 3ds Max 2011 and higher.
<adsk_SS_Environment>.UseAlpha : boolean
<adsk_SS_Environment>.Color : fRGBA color
<adsk_SS_Environment>.Map : filename
<adsk_SS_Environment>.Image_Frame_Number : integer
<adsk_SS_Environment>.skylights : node array
<adsk_SS_Environment>.Use_lights : boolean
<adsk_SS_Environment>.ImplicitLights : node array
<adsk_SS_Environment>.Sky : texturemap
<adsk_SS_Environment>.UseAlpha_connected : boolean
<adsk_SS_Environment>.UseAlpha_shader : texturemap
<adsk_SS_Environment>.UseAlpha_paramName : string
<adsk_SS_Environment>.Color_connected : boolean
<adsk_SS_Environment>.Color_shader : texturemap
<adsk_SS_Environment>.Color_paramName : string
<adsk_SS_Environment>.Map_connected : boolean
<adsk_SS_Environment>.Map_shader : texturemap
<adsk_SS_Environment>.Map_paramName : string
<adsk_SS_Environment>.TheList : maxObject array
<adsk_SS_Environment>.Shader_Version : integer