Line 1 Line 2 What line!?

I’ve been cloth diapering part time (at nights for now). I’m part of some cloth diapering communities on fb and I love reading everyone’s wash routine bc I have extremely hard water and always looking for tips etc. I’m too embarrassed to ask them what the heck they mean by line 1, 2, 3, etc. I tried googling it but there’s no answer for such a stupid question. Lol all I can think is what the heck do they mean!? There’s no line 1 line 2 line 3 on the washer. Is it a term for saying “first wash cycle” and “second wash cycle”?