Produces side-by-side page proofread safe intertext linking.
reference|The anchor to which you're linking|The page on which the anchor is located|The page on which the anchor is located in the Page namespace|Text of link}}
or more verbosely
reference|anchor=The anchor to which you're linking|mainlink=The page on which the anchor is located|pagelink=The page on which the anchor is located in the Page namespace|linktext=Text of link}}
Irrelevant parameters can be omitted with hopefully sensible results, e.g. if you aren't using ProofreadPage, you should leave out the third parameter, and the result will be a correct reference.
Also note that the link to the Page namespace page cannot be a relative link. It must be written out in full, i.e. Page:Example book.djvu/23 rather than ../23