Above it is an UnrealMaterial which provides some starting values for the unreal specific properties:
Base Color: Just like the Unreal equivalent it provides diffuse color for non metals and reflection color for metals.
Metallic: Controls how metallic the surface is. Keep it either 0 or 1 and only use grays for transitions between the two.
Specular: Used for micro occlusions, normal map related short range AO. It darkens the base color even while baking that channel so in the in-game material the “color*specular” operation should be omitted. The specular channel’s new default value is 0.5 which does not change anything. Higher values are not useful at this time.
Roughness: Defines surface roughness which affects specular highlight and reflection sharpness.
Emissive Color: The color of the light the surface emits.
Opacity: This value should behave as expected but has not yet seen thorough testing.
TessMultiplier: This property has no affect in MODO, it’s just here to allow the baking of data for tessellation density. The default value of 0.5 could be looked at as default, moderate amount of tessellation. Areas needing no extra triangles can be marked black while surface parts which use high frequency displacement are better set to white on this channel.
Aux. RGB: A color property for arbitrary use. It does not affect the surface in MODO but can be baked and used in UE4 for any purpose.