Character is not in T Pose - imported rig from Blender

Hello,

I imported a rigged humanoid character from Blender into Unity and it looks good for the most part, but I got an error, "Character is not in T Pose". I fixed the arms by rotating them 90deg into a T Pose, but I have no idea what Unity wants from the Hips.

What is the criteria for Hips to be OK? Higher? Lower?? in the hierarchy you can see that the Hips are connected to Thigh_L, Thigh_R and Spine.

i've attached the .blend file if you want to take a look

 

I found an option to 'Enforce T-Pose'. it fixed the problem, but I don't know what it did. I would like to understand what Unity wants, if anyone knows, feel free to chime in here

 

The hips look okay to me, but normally you'd have more bones in the back, and only branch out the shoulders when you get close to the neck. I found an article that has an example. I didn't read the article so I don't know how good it is, but the skeleton they show in the pictures is set-up more how Mecanim would expect.

http://nerdclub-uk.blogspot.com/2016/11/creating-simple-mecanim-ready-rig-for.html

 

thanks, kdgalla, interesting read. i'll search more through unity documentation too to see what they have to say too