mystery "fuel" line?, read, wondering if anyone knows Options

[mgnt232]

So doing my k-frame I broke a piece of a line off, but the piece that broke off the inside was completely filled with rust, and looking where it broke its all rust too. the whole line is looking like its ready to fall apart (rust wise).

I will get a pic tomorrow, but try to explain the best I can

If you were looking under the car (from engine to rear) you will see the 2 brake lines on left (i had to replace hose when i got my car) and the next line over (to the right) is the rusted through broken line. and next to it, are good, what I think are fuel lines.

The line I broke, isnt leaking anything, making the car run any different, or has any sound to it. Just wondering what exactly this line is lol

thanks everyone

[Bitter]

probably evap from the tank.