A style sheet is a document the copyeditor prepares that lists the grammatical conventions and the distinctive treatment of words (capitalization, hyphenation, favored spellings, etc.) within a particular text.
Information such as ““Fragments are acceptable with this author’s style” and “Split infinitives are acceptable with this author’s style” and the rules for hyphenation are found on the style sheet.Does the author prefer to lowercase or capitalize a full sentence after a colon? Is the author following British English or American English etc. are some of the details one is likely to find in a style sheet.
Style guides are readily available in the market. The Chicago Manual of Style is a popular style guide for non fiction. It is considered the bible of all style guides.