Hi Neuromuscular,

No, we are talking about the same thing.

+'ve stork test (stance phase - where you measure the PSIS and sacrum on the stance leg, not the hip flexion leg)
= unlocking of Wikipedia reference-linkSIJ = counternutation of sacrum relative to innominate or anterior rotation of innominate relative to sacrum

In other words, what you described above in your APAS test...

...which simply means stork test +'ve can produce the same results as your APAS test