properties.md

The Properties Object

Each Link Object may contain a Properties Object, containing a number of relevant information.

This document is meant to provide an exhaustive list of properties that can be associated to a Link Object, along with their semantics and usage.

Core properties

Key	Semantics	Type	Values
page	Indicates how the linked resource should be displayed in a reading environment that displays synthetic spreads.	String	left, right or center

page

The page property is meant to provide a hint to reading systems that rely on synthetic spreads to display more than a single resource at once.

In this example, the first page should be displayed of the left of a synthetic spread, the second page on the right.

"readingOrder": [
  {
    "href": "page1.jpg", 
    "type": "image/jpeg",
    "properties": {
      "page": "left"
    }
  },
  {
    "href": "page2.jpg", 
    "type": "image/jpeg",
    "properties": {
      "page": "right"
    }
  }
]

Extensions

Key	Semantics	Type	Values	Reference
contains	Indentifies content contained in the linked resource, that cannot be strictly identified using a media type.	Array	mathml, onix, remote-resources, js, svg or xmp	EPUB Profile
layout	Hint about the nature of the layout for the linked resources.	String	fixed or reflowable	EPUB Profile
encrypted	Indicates how a given resource has been encrypted or obfuscated.	Encryption Object	See the definition of the Encryption Object	Encryption Module

OPDS 2.0

While OPDS 2.0 itself is not an extension of the Readium Web Publication Manifest, it shares the same abstract model and syntax.

For this reason, it feels relevant to list the properties introduced by OPDS as well.

Key	Semantics	Reference
indirectAcquisition	Provides the expected download format for a publication, after an acquisition through an intermediate resource.	OPDS 2.0
numberOfItems	Hint about the number of items that are expected to be returned by the linked resource.	OPDS 2.0
price	Provides the acquisition price in a given currency.	OPDS 2.0