These are the proven interpretation of the FIFA rules of eligibility as they stand now and how they affect us.
These are proven by FIFA practice, not by speculation of how FIFA might or should interpret their own rules.
The thread can be searched for at any time and I can also clarify/edit the content in the thread opening post, should it be necessary.
IOI = Island of Ireland
BORN IN THE IOI
Most anyone born on IOI qualifies to play for the FAI.
One main exception is a NI born player who has already received a senior competitive cap for the IFA.
An IFA capped player at any other level, can switch to the FAI.
Precedent is Daniel Kearns.
DUAL NATIONALS BORN OUTSIDE THE IOI
Most, if not all, qualify because they have a parent or grandparent born on the island of Ireland, not just born in the 26 counties.
The precedent is proven for those players with NI born ancestors, as seen in the eligibility of Alex Bruce. Alex has one or both grandparents born in Co Down.
He was declared eligible for the FAI in 2006 under the eligibility rule, Annex 901, which is exactly the same as current eligibility rule17.
DUAL NATIONAL ALREADY CAPPED BY ANOTHER ASSOCIATION.
A dual national cannot switch if he has already received a senior competitive international cap.
He can change only once, if he has not already received a senior competitive international cap
eg. Ciaran Clark has been capped at youth level for the FA. He applied to switch to the FAI and that has been approved by FIFA.
At the moment, he is selected to play in a senior friendly, but not yet capped at the time of writing.
He is regarded as 'switched to the FAI' when he has received a cap.
Until he is capped, he is still at liberty to revert back to to the FA.
Clark can be named in the FAI squad, but if he is not capped, then FIFA do not regard that he has used his 2nd choice.
Should Clark change his mind before the game tonight, he can still choose to revert to England.
Once Clark receives a cap - even a friendly cap - he is regarded as using up his 2nd choice
DUAL NATIONAL, NOT ALREADY CAPPED.
The player has 2 choices until he receives a senior competitive cap.
Aiden McGeady is tied to the FAI, since he received his first senior competitive cap.
James McCarthy is not tied to the FAI until he receives his first senior competitive cap.