The rig should be orientated to the FRONT view with its face, along the UP axis with its spine, standing on the floor:
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Blender: looking along the -Y, +Z is up, the floor is X, Y
Maya: looking along the +Z, +Y is up, the floor is X, Z
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It doesn't matter if the rig is A, T, or any other pose as long as the conditions above are met.
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