These instructions assume you already have oXygen installed.

1. Get the DTDs

In your browser, go to one of the following URLs

• For NLM DTDs (that predate the official NISO JATS): https://dtd.nlm.nih.gov/
• For JATS DTDs: https://jats.nlm.nih.gov

Then navigate to the download page for the particular version you are interested in. For example, for from this page, click NCBI Book Set, then Version 2.3, then the link for the FTP site, ftp://ftp.ncbi.nih.gov/pub/archive_dtd/books/. From there it should be easy to find the DTD at ftp://ftp.ncbi.nih.gov/pub/archive_dtd/books/2.3/book-dtd-2.3.zip.

Allocate a stable directory on your machine to hold this DTD, download it, and unzip it.

Download that to some local working directory, and unzip it. If you want to plan ahead, we recommend this directory structure

├── niso
│   ├── archiving
│   │   ├── 1.0
│   │   ├── ...
│   │   └── 1.1
│   ├── articleauthoring
│   │   ├── 1.0
│   │   ├── ...
│   │   └── 1.1
│   ├── publishing
│   │   ├── 1.0
│   │   ├── ...
│   │   └── 1.1
│   └── test
└── nlm
    ├── archiving
    │   ├── 2.3
    │   └── 3.0
    ├── authoring
    │   ├── 2.3
    │   └── 3.0
    ├── books
    │   ├── 2.3
    │   └── 3.0
    └── publishing
        ├── 2.3
        └── 3.0

Be aware that not all of the Zip files on our FTP site are consistent in terms of the directories they create when you unzip them. You might have to do a little cleanup.

For our example, Books 2.3, unzip the dtd files into nlm/books/2.3.

2. Create a clean catalog file

For Books 2.3, copy catalog-v2.xml into a file named catalog.xml. Then, in a text editor, and delete every occurrence of the @xml:base attribute. For example, every occurrence of xml:base="file:///C:/Work/....", no matter what value is given, should be completely removed.

[If you are using Books 2.3, here is an already-cleaned version of the file. To use this, just save it to the same directory as the DTD.]

3. Set oXygen preferences

Note that these instructions haven't been vetted on multiple machines/architectures. They were written against oXygen XML Editor 17.0, on Mac OS X El Capitan. Depending on your platform, there might be significant discrepancies between these instructions and what you see.

Start oXygen, then create a new project and save it. Then got toFrom within oXygen, go to: Options > Preferences, then in the left side-panel > XML > XML catalog. Then click the [ Add ] button, and then navigate to the folder where you have the DTD and catalog, and select the catalog.xml file. Then click "Ok" once to go back to the main preferences dialog box.

Next, if other catalog files already appear in that list, then click the [ Up ] button to put the NLM/JATS catalog(s) at the top.

Before closing this dialog, make sure that:

• ‘Prefer’ is set to ‘Public’
• Verbosity is up to you, but we recommend, at least at first, to set it to "All messages", as it can help you trouble shoot OASIS catalog files.
• Finally, make sure that at the bottom, the "Global Options" radio button is selected.

4. Try it out

If you don't have your own XML file in the NLM or NISO format that you are interested in, check in the output of the DTD's Zip file -- there are usually sample XML files in the target format.

Open up your target XML file, and click the "validate" button (It looks like )

In the case of the Books 2.3 DTD, in turns out that both sample files are invalid according to the DTD. So if you can fix those problems, until the article validates.

Test also with a known good article.

If that works, then you are all set. Otherwise, take a look in the Errors tab in one of the bottom panes, or the Catalogs tab (you should see the Catalogs tab if you checked "verbose" in the preferences).