Train not included but 25% discount. Travel day used?

Hi,

My question:

In case a particular train route is not included in the interrail pass, but a 25% discount offered, does this cost you a travel day on your pass? As you have to apply for the discount at the station upon showing your interrail pass, I think that it will NOT cost you a day of your pass. However, I would like to be sure.

Thanks + cheers,

Threes