Many books are divided in parts. In some titles, parts are divided into (sub-)parts. Often these parts only have a only title and no further content. In those cases, an empty part page at brill.com is avoided by leaving out the @id-attribute in the <book-part>-element. If the id-attribute is included, an empty part page is presented at brill.com. See for example I Kollektive: Tumult, Aufstand, Avantgarde in: Im Gedränge (brill.com). The corresponding XML for this part is: 

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