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
orientation Suggested orientation for the device when displaying the linked resource. String auto, landscape or portrait
page Indicates how the linked resource should be displayed in a reading environment that displays synthetic spreads. String left, right or center


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 extension
encrypted Indicates that a resource is encrypted/obfuscated and provides relevant information for decryption. Encryption Object See the definition for the Encryption Object EPUB extension
layout Hint about the nature of the layout for the linked resources. String fixed or reflowable EPUB extension
media-overlay Location of a media-overlay for the resource referenced in the Link Object. URI Any valid relative or absolute URI EPUB extension
overflow Suggested method for handling overflow while displaying the linked resource. String auto, paginated, scrolled or scrolled-continuous EPUB extension
spread Indicates the condition to be met for the linked resource to be rendered within a synthetic spread. String auto, both, none or landscape EPUB extension

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



The orientation property defaults to auto and is mostly relevant for resources with fixed dimensions (images, videos), where the orientation has an actual impact on how the resource is displayed.

  "href": "page1.html", "type": "text/html",
  "properties": {
    "layout": "fixed",
    "orientation": "landscape"


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.

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