You may only use another person's work in a UHS file if you have their explicit permission, forward that permission when submitting your UHS file, and include a credit to the author in your own hint file. If any of these elements is missing, your file will not be accepted.
Using someone else's work -- even if you edit it into a slightly different format or change a few words here and there -- without their permission, constitutes copyright infringement. Anything you include in a UHS file must be written from scratch by yourself, or be used with the necessary permissions.
You may be under the impression that because many walkthroughs and FAQ's across the Internet copy from each other, it's okay to do so in a UHS file. That is absolutely not true. US and international copyright law protect any work from the moment it is written, unless the author explicitly says otherwise. You do not have the automatic right to reprint someting posted on a website or newsgroup in another format. Just because others do the same does not make it right. And if you've seen so many postings of the same work that you can't figure out who the real author is, don't use it.
Similarly, assume that game screen shots belong to the publisher of the game. Some people will claim that use of screen shots in a hint file constitutes "fair use" protected under copyright law. And some will say that any use of graphics in a hint file requires the publisher's permission. Either way, we prefer to err on the side of caution and therefore require that you get permission from the publisher to use graphics. If you want help getting a publisher's permission, let us know, and we'll be happy to contact them on your behalf.
No matter how experienced of a gamer you are, you may find that you get stuck from time to time in a game. If so, you may have to seek out help. There's nothing wrong with doing so, but when it comes time to write a UHS file, you must make absolutely sure that the file you write expresses the solution(s) in your own words.
And even if you do write a file all on your own, you should consider crediting the people who helped you through the game. Copyright law does not strictly protect ideas -- just the expression of ideas -- but giving credit to the people who gave you ideas is still the "right" thing to do. How much information you got from other people, and how common that knowledge is, will determine what credits are appropriate. (Of course, don't publish someone's name, e-mail address, or other personal information, if they don't want it published.)
For example, if you just got stuck on one or two puzzles, scanned a bunch of postings from a newsgroup, and saw 10 people all give the same solution, you probably don't need to list every single author of every posting you read. But if you wrote to anyone who helped you through the game personally or proofread your file, or if you used information unique to one or two sources, you should give those people a brief credit in your file. Also, if you used just one or two sources to help you through a large portion of a game or to fact-check your file, credit them for whatever assistance they provided.
Lists of cheat codes (and secret moves, points lists, hidden areas, and the like) are no less protected by copyrights than any other work. No matter how many times you've seen them listed, a list of codes was still written by someone initially, and that original author retains the copyright -- unless you can find proof that those codes were explicitly released into the public domain by their original author.
Of course, listing a couple of cheat codes here and there or including a points list may help the quality of your file. If you think that you need to do so, you may include them in your UHS file -- but make absolutely certain that you describe them in your own words. Don't just take someone else's descriptions and change an "an" to a "the" and call the writing yours. Collect the codes, test them, and write your own descriptions from scratch. Whenever possible, credit the original authors of whatever cheat codes or other secrets you have used within your file.
If you want to include tables or other collections of data -- for example, a list of hit points and attacks of all the monsters in a role-playing game -- you should determine these values on your own, or else get the permission of the author of the data.
While you can't copyright a single piece of data -- for example, that the red dragon in game X is worth 10,000 experience points -- large collections of data still may be copyrighted. Even if a table is just a bunch of names and numbers put together, the final expression of that data can still be protected as a unique work. Reformatting a table by changing the names of the headers, making data run in rows rather than columns, abbreviating things differently, or anything else along those lines does not change the fact that you are using someone else's work.
Once you learn information on your own, you may want to double-check that data with an external source to verify its accuracy. If you find one or two errors or omissions, you are probably safe including the corrected data in your own file with just a simple credit to the other source. But if you import tables from another source, you are still including that work and must get the appropriate permissions. (Of course, always verify external data by replaying the appropriate sections of the game, to insure the accuracy of anything in your file.)
Don't use it. Just because information might make your file better does not give you the right to use it. If you can't get permission to use something posted on a web site, you can still post the URL to the site or to a specific page -- assuming the site doesn't have some kind of policy against posting links to specific pages.
If you are just submitting your file to us for general comments or feedback, and it's clear that you do not intend the file to be a final draft, we will remind you of these copyright rules and ask that you correct any problems first. But it's always a very good idea to get permission first and add the relevant information only after you have the permission, just so you don't forget later on or have to make drastic changes to your file if the permission is denied.
You must send us copies of the permission to use any copyrighted works and include any relevant credits by the time you submit a "final" draft of the file. If we find that you have used anything without the appropriate permission, your file is subject to cancellation, and you will not receive payment of any kind for it. You will also not be allowed to write any further files, and in some cases, we may delete all of your existing files. In addition, you may be subject to legal action by the original author.