Should partOf of a AnnotationPage be an array or object?

[glenrobson]

Original raised by @jptmoore on slack: https://iiif.slack.com/archives/C18FHBKAQ/p1731497378271299?thread_ts=1731491354.710519&cid=C18FHBKAQ

One of the recipes going to the TRC tomorrow is on Annotation Collections. In this receipe the partOf of an annotation page looks as follows:

"partOf": [
            {
              "id": "https://preview.iiif.io/cookbook/309-annotation-collections/recipe/0309-annotation-collection/anno_coll.json",
              "type": "AnnotationCollection",
              "label": {
                "en": [
                  "Newspaper layout markup"
                ]
              },
              "total": 8,
              "first": "https://preview.iiif.io/cookbook/309-annotation-collections/recipe/0309-annotation-collection/anno_p1.json",
              "last": "https://preview.iiif.io/cookbook/309-annotation-collections/recipe/0309-annotation-collection/anno_p2.json"
            }
          ],

and follows the IIIF guidance on partOf (https://iiif.io/api/presentation/3.0/#partof):

"The value must be an array of JSON objects. "

but the Web Annotation Model says (https://www.w3.org/TR/annotation-model/#model-35):

"The relationship between the Page and the Annotation Collection that it is part of.
Each Page SHOULD have a exactly 1 partOf relationship, with the value being either the IRI of the Collection or an object with some or all of the Collections properties, including at least its id."

As this is an AnnotationPage linking to a AnnotationCollection, which standard should we follow?