What are XML documents?

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Summary: XML is a specification for structuring data in a file. Exactly what data, and what it might be used for, is not part of that specification.

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Yes and no. I can tell you what XML documents are, but I can't tell you what those XML documents are.

But I do have some suggestions for cleaning things up.

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XML stands for "eXtensible Markup Language" - it's nothing more than a specification for structuring data, and not much more.

It's that "not much more" that's going to be our problem here.

The issue is that while the fact that it's a ".xml" file tells you that it's some kind of structured data, it doesn't tell you at all what the data is, or who produced it. Much like a ".dat" file there's just no way to know what a ".xml" file contains without knowing more about it.

Now, unlike a ".dat" file, a ".xml" file is text, so one approach might be to open up the file in notepad and take a peek. The problem here is that it's extremely likely that the results will still be incomprehensible to most folks. In other words, you might be able to look at the data, but that still won't help you figure out what it is.

There are several approaches to dealing with unknown files like ".xml" files you don't recognize:

• Do nothing. In reality, this is my preferred approach. As long as they're not causing you a problem in some way, then there's no real incentive to do anything about them. "If it ain't broke, don't fix it" really does apply to computers.

• Rename them and see what happens. This is a quick test to see if you can rename a file - if you can't it's possible that some program is using the file, which of course may help identify what the file is all about. How can I find out who is using a "file in use"? will help you determine if the file is in use, and by whom. When renaming, it's best to rename the extension - meaning you would rename "a.xml" to something like "a.xmlsave". If you find you need the file you can then rename it back.

• Back it up, delete it and see what breaks. Backing the file or files up first is important because it may be a while before you find out that you really did need what you deleted. You can burn them to CD or copy them to another machine. Just make sure that you can recover them a week or a month later when you find out that for some reason you really didn't want to delete them in the first place.

• Take your chances. You can delete the file and deal with the consequences, whatever they may be. Naturally I do not reccommend this approach, particularly when backing up first is such an easy thing to do.

The bottom line here is simply this: knowing that a file is an XML file tells you almost nothing about it. You need to know what it contains, or who created it, in order to really know what the file's purpose is.

Related:

• Ask Leo! - What's a '.dat' file?

• Ask Leo! - How can I find out who is using a "file in use"?

• Wikipedia - XML

Article C3355 - April 20, 2008