Online Fare Queries

[Bawner]

I have a couple of questions regarding online bookings on irishrail.

Trying to book fare to Sligo. Some fares are listed as sold out. I presume this means that the online fares are sold out but I could still buy ticket in Connolly.

There are other fares listing the price but with an orange box with a white x which means "No online ticket available / not reservable" What exactly does this mean - the fare is not available at all or you can get the fare at a station? I presume there's a difference between this and the sold out one above.

Irish rail site doesn't seem to shed any light.