Hi, first of all thanks for this plugin!
We are using the 1.0.0.7 release for our 3.5.0-5 LTS OMP; re-registering some DOIs we noticed that the plugin is not includind Prefix field in titles...
Example: this monograph's](https://libri.unimi.it/index.php/milanoup/en/catalog/book/45)%27s) title "Le tipologie di albero nelle drupacee" is made by "The" (an article in italian, corresponding to the english "The") in Prefix field and "tipologie di albero nelle drupacee" in Title field

The resulting <title> in XML prepared by the plugin is "<title>tipologie di albero nelle drupacee</title>" instead of "<title>tipologie di albero nelle drupacee</title>".
Without "Le ", the DOI can't be updated because Crossref do not recognize that the book is the same and the deposit results in the error below.
We think the problem is in rows 193-198 of this file:

    // 2. titles (required)
    $bookMetadataNode->appendChild($this->createTitlesNode(
        $doc,
        $publication->getData('title', $locale),
        $publication->getData('subtitle', $locale)
    ));

but we do not understand how to change to consider Prefix field if not empty.

We have a OJS 3.5 installation too, and we noticed that the system crossref plugin takes into account the Prefix field within the call (row 114 of ojs-3.5.0-5\plugins\generic\crossref\filter\ArticleCrossrefXMLFilter.php)
array_keys($publication->getTitles()
but we don't know if and how getTitles() can be used in OMP.

Can you help?
Best regards
Stefano

Deposit error

ISBN "9791280325235" has already been assigned, ISBN assigned to other title: Le tipologie di albero nelle drupacee/9791280325235

<doi_batch_diagnostic status="completed" sp="ip-10-4-0-83.ec2.internal">
<submission_id>1769065052</submission_id>
<batch_id>milanoup_1790093441</batch_id>
<record_diagnostic status="Failure" msg_id="24">
all doi's under the current book element
ISBN "9791280325235" has already been assigned, ISBN assigned to other title: Le tipologie di albero nelle drupacee/9791280325235
</record_diagnostic>
<batch_data>
<record_count>1</record_count>
<success_count>0</success_count>
<warning_count>0</warning_count>
<failure_count>1</failure_count>
</batch_data>
</doi_batch_diagnostic>