Clarification of Oct-Encoded Per-Vertex Normals

[plutoscarab]

The paper that the spec refers to that defines oct encoding of normals talks about the snorm8 data type, which they define on page 6 as having an integer representation of -127 to +127. This spec uses unsigned char for the values, which is 0 to 255. Do we subtract 128, or do we cast to signed char? And either way we can end up with -128, so how is that handled?