23 | EPUB Validation

In this section, we run projectx through validation to check the code for errors.

File Version

In this section, work in the freshly saved revise_projectx.epub file.

EPUB Validation

How important is validation? REALLY, REALLY IMPORTANT.

That's all I'll say on the topic. Much like the table of contents, Sigil makes this process easy for us.

Hit the Tools menu again and select Validate EPUB with FlightCrew.

Our goal is — once you click Validation — to receive the ‘No problems found!’ message.

Not everyone will be this lucky. Sigil, however, does an excellent job explaining where something is wrong, and what is wrong. Google is your friend in this regard. Our wonderful EPUB community on the web has done an awesome job of documenting validation problems.

I've found from my own battles with EPUB that most validation errors occur when I've had to delete or revise something like an image, cover art or anything else related to the manifest. It can be tricky to find and cleanup every reference to a file or tag in an EPUB. The more you play around, the more you discover, so experience is your best friend in this regard.

The Scandal file, if everything’s been done as outlined in the tutorial, shouldn’t return any issues. This is where NOT using Word’s ‘filtered’ HTML makes all the difference. Our files are clean and very lightweight in comparison.

NOTE: You will not come up with "No problems found" in the kindle_projectx.epub version. This is because we have included a cover art image with absolutely nothing utilizing that image file. Even though this surfaces as a validation error in FlightCrew (though interestingly, not in the IDPF validator) your file will still convert without any issues.

The returned-result message I'm talking about will look like this:

OEBPS/Images/***image name***.jpg | This resource is present in the OPF <manifest>, but it's not reachable (it's unused).

Again, this is expected, and nothing to worry about. This is fine for the MOBI version and will not affect end-product conversion or performance.

Play It Again, Sam

Now we validate again using the International Digital Publishing Forum's EPUB Validator.

Yes, it's necessary to do this twice. I think this version is a bit more strict than FlightCrew on certain things, so it's always a good idea to run through both.

Again, if you encounter errors, Google them. Someone out there will have had the same error and posted about it; you will find the answers if you look for them.

ACTION: Save

Once projectx has passed validation, use SaveAs to rename the file passed_projectx.epub.

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