Is Tangent Space really necessary?
Little things are seldom documented in the Sansar Release Notes. And searching old release notes is quite time consuming. Also, some things get into a minor update and they too are not consistently documented.
The Sansar documentation will grow stale when changes are made to the program and the updates are pushed out and the documentation is not done for days or weeks.
One recent change came to light when I asked if the export from Blender still required the Tangent Space be selected in the export panel:
The answer came back to me from David who wrote: “We have also been told that it is no longer needed. If tangents and binormals information is needed and is not present there will be a problem with the model appearance on upload. This will cause a problem with the shader. You can read about tangents and binormals online. For example: https://gamedev.stackexchange.com/questions/51399/what-are-normal-tangent-and-binormal-vectors-and-how-are-they-used If the converter can get vector cross products across the entire mesh then it has all the info it needs.
So, I took that as a “no longer needed.”
Asking for Documentation
When items such as these come to light, the best we can do is request an update to the documentation. Everyone can help out on this topic by writing requests for documentation here. (They just call it “Documentation” when you get to that page.) I would think it would be called something like: Documentation Requests, but Linden Lab must have held that focus group without me. The odd thing is that this link goes to a subsection of “Community”. So do not look for it under the Knowledge Base which is where I instinctively looked for it. And that is if you can find the Knowledge Base.
The Knowledge Base
Do not search for a “Knowledge Base”. The part that is mostly the Knowledge Base is on the left half of this page which also include the right half where you find the “Community Forum“. And note that the Knowledge Base comes in two flavors. To find the creators flavor of knowledge called Creating in Sansar, scroll down below the section dedicated to the flavor that is meant for visitors called Exploring in Sansar.