Subtitles delay

[Iria]

I read the Faq on subtitles use, but is does not say what is the unit used for delay
What do I have to write in the delay box? Seconds? + or -?
I can't find it anywhere

[zorglub]

It's tenth or seconds .

For + or - ... well, try, and you will see It's always quite hard to remember

[Guest]

I think its tenths.
To delay appearance use +.
I think there is a limit of 50 min but i have not confirmed that.