You can use any train of DB (german rail) or Sncb (belgian)
The Thalys is reservation compulsory
The ICE is optional means you can buy a reservation if you wanna have a seat for sure.
Thank you. What does domestic and international me in regards to the countries I can travel to. I assume international means around just Europe and not anywhere else in the world?
Does domestic mean just within that country for example, I can only use the train listed under domestic around Germany, or could I get it to somewhere outside of Germany (eg Brussels) or does that class as international travel?
Donestic just within a country
International means cross atleast one border
Please ignore the OCP & GP Its a special option (how tickets are sold) this form is quite complicated for starters