According to the pass conditions, every train should be written on a new line.

I practice, however, staff are usually fine if you a complete journey on one line.

In any case, make sure you have one or more spare pages.

Once I was told by a conductor in DK that indeed every single train has to be noted apart, so I had to correct it. As I had a 2 month pass and used it quite often, I just wanted to save lines.-stating v.v. for the return on same day/same sector.

The reason behind this is that in many countries there is now more as 1 train-comp. and the revenues are divided up in the end by very diligent people who scan all the passes sent for to country/operator. This is in fact the main reason why these new electronic apps were introduced-now it goes much more automatic.