I love your clean code, and your use of generic blocks.
With your permission, to benefit our readers, I have exported your code and design so we can learn from it.
I have also added a bug fix for your check procedure, to avoid false positives in that big JOIN test, where a three letter X sequence or OOO might span across pieces of your big JOIN.
gato123456_with_JOIN_fix.aia (7.1 KB)