what,s the real zero point???

[loadcc]

in my mind ,there are three zero point, one is standing (without aiming) zero point; one is aiming zero point; last one is trigger zero point.
which one should landed at the bullseye???
or no one should be ?or our body keep little tension when aiming at bullseye??
i found my score is unstable when aiming zero point towards the bullseys.
does that zero point balance without any body tension is broken easily?