Morning everyone

I want to seek clarity on the retreat line rule. There’s mixed opinions within the comments but I would like to confirm the following scenario. 

1) When the keeper has it in their hands from open play does the retreat line rule apply

2) is the retreat line the halfway line. I’ve seen articles suggesting it’s an imaginary line around 1/3 into the opposing teams half. 

If anyone can quote the rule and/or an extract that would be great

Thanks in advance 

Steve