a^{a1}_{c0,a0} b^{c0}_{a2} a+(a0) a+(a2) a-(a1)
-a^{a1}_{c0,a0} b^{c0}_{a2} eta1^{a2}_{a1} a+(a0)
+a^{a1}_{c0,a0} b^{c1}_{a2} eta1^{a2}_{a1} a+(c0) a+(a0) a-(c1)