[Max Script] Edit UVWs texMap arrays out of sync?

dimwalker

I have multisub material. With macrorecorder enabled I can see how max creates texMapList and texMapIDList when I open EditUVWs window:

$.modifiers[#Unwrap_UVW].texMapList.count = 17
$.modifiers[#Unwrap_UVW].texMapIDList.count = 17
$.modifiers[#Unwrap_UVW].texMapList[1] = Checker ()
$.modifiers[#Unwrap_UVW].texMapIDList[1] = -1
$.modifiers[#Unwrap_UVW].texMapList[2] = Bitmaptexture fileName:"D:\SVN\...\xxx.tga"
$.modifiers[#Unwrap_UVW].texMapIDList[2] = 0
...
$.modifiers[#Unwrap_UVW].texMapList[17] = Bitmaptexture fileName:"D:\SVN\...\yyy.tga"
$.modifiers[#Unwrap_UVW].texMapIDList[17] = 13
$.modifiers[#Unwrap_UVW].TextureCheckerMaterial = PhysicalMaterial ()

Now comes confusing part. There are 2 checkers at the start of texture list: Texture Checker (UV_Checker.png) and CheckerPattern (Checker).

texMapList.count and texMapIDList.count both return 17 and if I try to get $.modifiers[#Unwrap_UVW].texMapList[18] it gives "undefined", but if I select last texture from the list manually, macrorecorder shows this action as

$.modifiers[#unwrap_uvw].unwrap.setCurrentMap 18 

I can set 18th id, but can't get it from those arrays.

So is there another third array that stores proper values or how can I synchronize get/set states of texMap arrays?