Rain leader markings

I’m in Minnesota, doing practice tests studying for my jman test. I Can’t find in the code books what intervals rain leader piping has to be marked besides where it goes through walls/ceilings. Can anyone please tell me what the intervals are & moreso, where it’s found in the book? In the rain catchment section, the “markings” section doesn’t give the answer & I can’t find it anywhere else.

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