Added

• Add volume shading support by @msuzuki-nvidia in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/169
• Add a discussion of the difference between entering/exiting light transport by @portsmouth in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/168

Changed

• Making roughness ranges all [0,1] by @portsmouth in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/160
• Define the glossy-diffuse albedo to explicitly correct for darkening by @portsmouth in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/165
• Rename base_roughness to base_diffuse_roughness by @virtualzavie in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/175
• Update behavior of specular_weight, specular_ior_level, coat_ior_level by @portsmouth in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/157
• Subsurface refactor by @portsmouth in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/171
• Align example material names by @jstone-lucasfilm in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/177
• Update specification and reference to v0.4 by @jstone-lucasfilm in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/178

Fixed

• Remove unused transmission roughness from reference graph by @portsmouth in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/173