Fantasy readers and writers are familiar with story bibles and glossaries that define character names, locations, objects, unique terms, even created languages used within the book for the reader. I'm a sucker for a solid, multipage glossary myself. It's one of the best parts of writing and reading fantasy for me. 

These tools also help the author keep their worlds and personas consistent across several or more books that may span years, both within the storylines and in the writing of the books themselves.

Meaning Tall-and-Godly won't have copper waves in one book and a jet-black ponytail in book two. 😜

Editors find these files useful as well; including them in your submission packet for any stage of editing is welcome. But we also may take them a step or so further and create a style sheet as we work. 

My copyedit and line edit packages include the creation of a style sheet for the novel. It outlines such things as:

• character names and spellings as they should be
• location names
• words that should be capitalized, both unique to the story and in general
• whether to use the Oxford comma or not
• grammar rules that frequently occur
• punctuation guidelines that should be followed
• the dictionary used for spellings
• the reference guides/style guides used as guidelines
• author preferences of spellings, word forms, languages, slang words, really anything the author wants a certain way in their book  
• word forms that are hyphenated and when they are hyphenated or not
• Fonts, font sizes, spatial alignment of chapter headings, quotations, or other text treatments within the book

Other things show up also; the document is frequently several pages long.

After the edit, the author then has this as a reference item and can add to it as they write forward. They can also copy general items from it to use in style sheets for unrelated books to keep parts of their voice consistent. Why redo what's already been done?  😎