Paper recycling is the process of turning waste paper into new paper products. There are three categories of paper that can be used as feed-stocks for making recycled paper: mill broke, pre-consumer waste, and post-consumer waste. Mill broke is paper trimmings and other paper scrap from the manufacture of paper, and is recycled internally in a paper mill. Pre-consumer waste is material which left the paper mill but was discarded before it was ready for consumer use. Post-consumer waste is material discarded after consumer use, such as old corrugated containers (OCC), old magazines, old newspapers (ONP), office paper, old telephone directories, and residential mixed paper (RMP). Paper suitable for recycling is called "scrap paper", often used to produce molded pulp packaging. The industrial process of removing printing ink from paper fibers of recycled paper to make de-inked pulp is called de-inking, an invention of the German jurist Justus Claproth.