Hi,
I got character animation send to me as .abc (it has UV).
I would like to render only Position AOV with Mantra. Default one in mantra is World Position.
Can you please give advice or example how to create Object Position AOV so in Nuke I can make mattes for certain part of character and these will stick.
Thank you.

Object position is still unlikely to stick to a character since it's deforming. (unless it's like robot or something). Create a rest attribute on the mesh before the bone deform or blendshapes animation. Then export rest in the material and add the export to the image planes section of the render node.

Edit:
oh you have an alembic. In that case the pref would have to come from a bind pose in the animation, or some pref attribute in the file. Without that, best you can do is freeze a frame and use that as rest.