non-conforming meta element name="Sigil version"

[derrickoswald]

It seems that Sigil adds a non-conforming meta element to the metadata in the opf file.

It adds (at least in the Linux flatpack Version 2.0.1, Qt 5.15.10 that I have):

<meta name="Sigil version" content="2.0.1"/>

From the ePub 3.3 specification of metadata contents, the meta element can only have attributes:

• dir [optional]
• id [optional]
• property [required]
• refines [optional]
• scheme [optional]
• xml:lang [optional]

Is there a way to have Sigil insert a correct meta element, e.g. creator with a role:

<dc:creator id="software">Sigil 2.0.1</dc:creator>
<meta refines="#software" property="role" scheme="marc:relators">oth</meta>

or any other correct syntax?

I see this previous question from 2016, with an answer that basically says to build the code yourself, or use an output plugin.

For the "build it yourself" choice, I've done that on Linux, patching together various instructions (what a mess that is, but that's a different thread), but sadly, I see no icons in the UI so it's not a usable version.

Would the second "output plugin" option really work? There is only half an interface:

# metadata get/set

    def getmetadataxml(self):
        # returns a utf-8 encoded metadata xml fragement
        return self._w.getmetadataxml()

but sadly, there is no setmetadataxml() method.
Any suggestions?

[BeckyEbook]

The simplest workaround for today: use SIGIL_DISABLE_VERSION_META environment to disable the addition of this entry to the metadata.

[DiapDealer]

Originally Posted by derrickoswald

I've done that on Linux, patching together various instructions (what a mess that is, but that's a different thread)

As the person who volunteers his time to keep the Linux build instructions as up to date as possible, you'll want to tread lightly in that different thread (should you choose to start one).

[KevinH]

And epub2 style informational metadata is perfectly legal in epub3 and by spec must be ignored.

So there is no need to change anything. Just disable it using the provided environment variable.

[Doitsu]

Originally Posted by derrickoswald

From the ePub 3.3 specification of metadata contents, the meta element can only have attributes:[...]

Not really, since the specs also mention that the epub3 specs are based on HTML5, and in HTML5, the meta tag may have a name attribute.
Moreover, several of the epub3 sample files endorsed by the EPUB3 Working Group contain <meta name="cover" content="cover"/> entries. For example: Wasteland and Page Blanche

Originally Posted by derrickoswald

[...]

    <dc:creator id="software">Sigil 2.0.1</dc:creator>
    <meta refines="#software" property="role" scheme="marc:relators">oth</meta>

or any other correct syntax?

Even though another well-known epub app does this, technically you can't use <dc:creator> for apps, because that entry should only be used for persons, organizations or services that create documents.

BTW, if you want to find out whether an epub book is valid, simply check it with EPUBCheck.

Originally Posted by derrickoswald

[...]but sadly, there is no setmetadataxml() method. Any suggestions?

You're mistaken, there's, of a course, a bk.setmetadataxml() method.
You might want to download the latest version of the Sigil Plugin Framework Guide.

[derrickoswald]

Originally Posted by BeckyEbook

The simplest workaround for today: use SIGIL_DISABLE_VERSION_META environment to disable the addition of this entry to the metadata.

For the flatpak version, this command does the above:

flatpak override --user --env=SIGIL_DISABLE_VERSION_META=true com.sigil_ebook.Sigil

[derrickoswald]

Originally Posted by Doitsu

You're mistaken, there's, of a course, a bk.setmetadataxml() method.
You might want to download the latest version of the Sigil Plugin Framework Guide.

Sorry, because of the comments in the post from 2016, I was looking at the output container documentation (line 135 of outputcontainer_py.html in Sigil_Plugin_Framework_rev14.epub):

# metadata get/set

    def getmetadataxml(self):
        # returns a utf-8 encoded metadata xml fragement
        return self._w.getmetadataxml()

which suggests there is no setmetadataxml() method.

Is it not true that an output type plugin is passed an outputcontainer object?
If the outputcontainer object does have a setmetadataxml() method, should the documentation be updated?
If it does not have a setmetadataxml() method, should it?
If not, would an edit type plugin's changes to delete the meta tag not be overridden by the save operation (in the case that environment SIGIL_DISABLE_VERSION_META didn't exist to do this)?

[DiapDealer]

setmetadataxml() is for updating the metadata of the existing epub. Since an output plugin can be used to output whatever format a dev desires, there didn't seem to be much sense in providing an epub-only setmetadatxml() method in the output container object. Much like there is no epub-only getmetadataxml() method in the input container object. We couldn't guarantee either would work in all situations.

If one is starting from an epub and ending with an epub, it would make more sense to me to use an Edit Plugin to modify the metadata. If one needs to preserve the original, then Save As and/or Checkpointing would come into play. Using the output container to create a new epub with slightly tweaked metadata seems counter-productive to me.