I guess that there are some of You here that are, or work for an ICANN Accreditatided Registrar company. So maybe someone here knows how things work.

To transfer an domain from one Registrar to another You need an AUTH CODE.
You will have to write in this code (at the new Registry) whenever You set up an Transfer.

Where will this Code be checked?

Will it be checked against the TLD Registry (say at PIR.ORG for a dotORG domain)
or will it be checked against the database at the loosing Registry?

And if You cant get the Auth Code at the loosing Registry, can it be generated at the TLD Registry?

Sammy :)

The auth code are generated on the loosing registry. There is no reason why the loosing registry will not release the code to you, if they really don't you can report to ICANN

My understanding is that auth codes are generated by the current regisTRAR, and sent to the regisTRY real-time. When a transfer takes place, you render the auth code (got from the current/losing regisTRAR) at the new/winning regisTRAR, it will then be sent to the regisTRY for verification.

My understanding, perhaps startgate can confirm.

Auth codes are generated by the registrar, and submitted to the registry. When you transfer, the gaining registrar will check the auth. code you provided with the auth code that the losing registrar provided to the registry.