the seal was a seal of a king. He placed a seal on the letter of proclamation they were sending to another king or whoever, The seal (unbroken) proved the the words in the letter was a proclamation of the king.
This is what the seal is. not a seal as in preventing you from getting out, why can they not see this? The seal is the HS guaranteeing our salvation. when we are delivered to the father.
I gave a rather thorough treatment on this and the entire topic in question many pages back. Those that believe in the born, unborn, born, unborn logic, bypassed it for good reason I believe. None even dared comment on the details within.