Oce PP18C Operation Manual page 21

ADVANCED OPERATION GUIDE
5 Pull the release lever on the left side guide and slide to the desired paper
size.
Release Lever
6 Pull the release lever and slide the paper stopper to the desired paper size.
When using non-standard size paper, move the paper guides and paper
stopper all the way out, insert the paper, then adjust the paper guides and
paper stopper to the size of the paper. Adjust them so that they are in light
contact with the paper.
Handling Paper
Paper Guides
Release Lever
Paper Stopper
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