It is said in Lie Algebras in Particle Physics 2ed - From Isospin to Unified Theories (Georgi, 1999) p.285, Georgi said that

$\rm SO(10)$ grand unified model restores the parity symmetry that was lost completely in $\rm SU(5)$ model.

However, it seems to me that the spinor representation 16 alone in $\rm SO(10)$ model breaks the parity symmetry. Can experts clarify the conflict?

It is possible that the parity here means something not just $P$ but mixed with other internal symmetries such as automorphisms (inner or outer?) of the gauge group. What exactly does Gerogi mean?

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