Flush items from belts, the same way you can from pipes.

[reincarnationfish]

So... when you click on a pipe you get a box that tells you what the whole pipe section contains and allows you to click to flush one or more fluids from the pipe if by you've somehow made a connection mistake and managed to mix fluids or let the wrong fluid in.

Doing the same with a belt only shows you what is on that specific belt cell though, even though the game can now use the circuit network to check on the contents of the whole belt section. It would make more sense for clicking on the belt to highlight the whole belt section, tell you the contents of the whole section and have an option to flush all of one item from it, by locking the belt sending construction bots to remove the offending items, then unlocking it again.

Anyone who has played for a while will know how annoying it is to accidentally bleed the wrong items onto a belt, often not noticing until ten minutes later when the entire factory has ground to a halt because of it. The easiest way to deal with this right now is to walk the character along the belt with the f key help to hoover them all up. But in space age, you might not be able to do this because you're on another planet. This would make these messes so much easier to tidy up!