Sigil 1.9.30 and unsupported media-type

[z537815]

Running Sigil 1.9.30 on Windows 10.

I recently got hold of an Epub that has Sigil, upon loading this epub, complaining about an unsupported media-type "Application/XML" for a file in the OPF. Sigil replaces this with a temporary media-type, but strongly advises to correct the OPF.

Surely "Application/XML" is supported? Or am I missing something?

TIA for any info.

[KevinH]

I think you are missing something ...

What file was it?

The proper media-type for xhtml is "application/xhtml+xml".

In fact the "application/xml" media type tells you almost nothing about the kind of file as pure xml can represent many different file types.

And pure xml islands in the spine are been long deprecated by the epub standard.

These are the specific xml based media types recognized by Sigil and current or previous epub specifications:

"application/xhtml+xml" (.xhtml)
"application/x-dtbncx+xml" (.ncx)
"application/oebps-package+xml" (.opf)
"application/pls+xml"; (.pls)
"application/smil+xml" (.smil)
"image/svg+xml" (.svg)
"application/ttml+xml" (.ttml)
"application/oebps-page-map+xml"
"application/vnd.adobe-page-template+xml"

Note: xml and therefore xhtml are case sensitive so the media-type is as well.

For a more complete list of recognized media types see Sigil's source code here:

https://github.com/Sigil-Ebook/Sigil...MediaTypes.cpp

[z537815]

I (perhaps naively) assumed Sigil would support ALL media-types, and having found that "application/xml" does actually exist, couldn't understand this error-message.

However, I "fixed"(?) it by changing the media-type from "application/xml" to "application/xhtml+xml". This seems to work. The error-message is gone.

[KevinH]

The epub specification itself indicates the media types that are recognized. A reader can choose to support additional ones but need not. Use of anything outside of the recognized set requires fall backs.

So you did indeed need to truly "fix" it if you wanted an epub that meets the spec.

See https://www.w3.org/TR/epub-33/#sec-core-media-types