Unused sheen default value?

[pablode]

Hi! The spec describes a default value of 0.8 for the weight of the sheen BRDF:
https://autodesk.github.io/standard-surface/#closures/sheen

However, in the implementations, the value is actually set to 0.0:

standard-surface/reference/standard_surface.mtlx

Line 51 in b34e081

<input name="sheen" type="float" value="0" uimin="0.0" uimax="1.0" uiname="Sheen" uifolder="Sheen" uiadvanced="true"

standard-surface/reference/standard_surface.osl

Line 177 in b34e081

float sheen = 0,

Is this because the layer is optional and the input serves as both weight and toggle?