Bicycle "owner's manuals" have always been rather minimal. Those from Asian manufacturers have often been full of misinformation, oversimplification and amusing mis-translations.
This manual is pretty typical, used for all Centurion and Diamondback models from the bottom to the top of the line.
The identical pages probably were used by quite a few other manufacturers. It is offered mainly for amusement and because owners of classic bikes often go to a lot of trouble trying to obtain the owner's manual for their bike, only to be sadly disappointed when they discover what a pitiful document it is.
I have added links to some of my articles on the relevant pages, where you can find more useful information.
Click on the small images below to see a scan of the page; Click on the page scan to go on to the next page.
Note that the Centurion name lives on in an unrelated bike brand from Denmark.