This document describes the set of use cases generated for Annotation and Social Reading within the W3C Digital Publishing Interest Group, in coordination with the Open Annotation Community Group.
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Annotation is a pervasive activity when reading or otherwise engaging with publications. In the physical world, highlighting and sticky notes are common paradigms for marking up and associating one's own content with the work being read, and many digital solutions exist in the same space. These digital solutions are, however, not interoperable between systems, even when there is only one user with multiple devices.
This document lays out the use cases for annotations on digital publications, as envisioned by the W3C Digital Publishing Interest Group, the W3C Open Annotation Community Group and the International Digital Publishing Forum. The use cases are provided as a means to drive forwards the conversation about standards in this arena.
2. Use Cases
The use cases are divided into five sections: annotations that target only the entire publication, annotations that target a particular part of a publication, more complex annotations, the publication of annotations and finally use cases that are directly related to accessibility.
2.1 Annotations Targeting the Full Publication
2.1.2 Tagging a Publication
A user wishes to organize their personal digital library by tagging the publications that they have access to. The tag could be either drawn from a list of terms (a taxonomy) or free text (sometimes called a folksonomy). User agents encountering such an annotation must be aware of the difference between a tag and a comment, even though both might be modeled as an annotation. Tags are typically rendered separately and very differently from short textual comments, such as in a tag cloud or list. The user then wishes to view their library partitioned via the tags. The user may wish to share their tags with other users to help the recipient categorize their own library, or find publications of mutual interest.
- Colleen has a collection of works of various types in her library about chemistry, science fiction and the renaissance. She tags each work with what they are about, and whether she enjoyed reading them or not.
- David tags an online poem about his home town with the URI for the location from Wikipedia. He publishes this annotation so that others can find it.
2.1.3 Structured Review of a Publication
A user wishes to provide a structured review of a particular publication, including pre-defined fields such as "star" ratings for quality, cost, entertainment or other domain-specific information. The review could also include a full text description, such as the comment in the first use case. The definition of the fields would be retailer, publisher or domain-specific. In the scholarly domain, this could be expected to provide a distributed and standardized peer-review system, rather than the current use of vendor-specific interfaces. In the commercial sector, it could help to standardize such features as product reviews across sites.
- Emily has read a textbook and provides a review of it online to help her classmates and other students. She gives it ratings on value for money, ease of use, ease of understanding, and overall quality, plus a long form description of the work.
- Fabio is reviewing a scholarly article for an academic publisher. The publisher requires various fields to be completed, such as relevance to the journal, novelty of the research, and quality of the experiments described. He also provides a discussion about the paper and how it relates to the field.
2.1.4 Comment Maintained Separately from Annotation Document
A user wishes to link an existing web resource, such as a blog post or uploaded video, to the particular publication that it is about. The comment could be any online resource, in any format. The user wishes other readers to be able to see the resource linked to the publication, and potentially before they purchase or download it as well as afterwards.
- Gretchen uses a mobile device to take a video of herself discussing a work that she has just read for a book club. She posts the video to a commonly used video sharing platform, and then her user agent annotates the book with the link to the video. She then shares the annotation with the members of her book club.
- Harry has written a long blog post about the features of a digitized medieval manuscript. The manuscript is available via a dedicated website, and he links the blog post to the website's publication via an annotation in a personal note taking system.
2.2 Annotations Targeting Specific Segments of Publications
2.2.1 Bookmarking Current Reading Position
A user wishes to have their user agent record the location they have read up to in the publication, either with a manual or automatic bookmark. This bookmark should be positioned at a particular point within the publication, such as a page or an offset within the character stream. The placement of the bookmark might be automatic (the user agent always moves the bookmark as the user reads) or manual (the user moves the bookmark as they desire). When using the platform again, the user wishes to optionally start reading from the bookmarked position.
The user also wishes to share this position with others to show how far through the publication they have progressed. This might be publically shared for bragging rights, shared semi-publically such as a reading group or class, or shared privately between platforms that the user has access to in order to maintain the position between devices.
- Madeleine is reading a fantasy book as she commutes to work on the train every day. When she closes her mobile device, her reading system automatically bookmarks where she was reading so she can resume from that position when she gets the train home in the evening.
- Nigel is studying for an exam and creates bookmarks in his textbooks and required reading documents at home. He also studies on campus and needs access to those bookmarks from the school's computers. He does not want other students to see his bookmarks, as he is competitive and wants to be the top of the class.
2.2.2 Highlighting a Span of Text
A user wishes to highlight a span of text in a publication for emphasis. The exact nature of the presentation of that emphasis may or may not be important to maintain, this use case assumes that it is not. The emphasis might be to mark a passage of particular importance, a typo or other mistake, something to cite in another document, to bring to the attention of other readers, or to mark two such selections for comparison. The user may wish to share the highlight, and certainly wishes it to be accessible on multiple platforms to which she has access. In this use case there is no requirement to provide a comment or body of the annotation, simply to record a highlighted span of text.
- Olivia is preparing to publish a newspaper article and is doing background research. She highlights various sections of other publications in order to later come back to them and decide if she should include them as quotes in the article or not.
- Peter is proofreading his own term paper and highlights areas that he needs to work on. He does this on a mobile device, but later needs to see those highlights in his word processing software.
2.2.4 Annotating Embedded Resources
A user wishes to make a comment about a particular resource that is embedded as part of the publication, such as an image or video. In the general case, the user would expect to somehow select the embedded resource and then launch the interface for adding comments in the same way as commenting on text. The embedded resource may be of any media type, but for this use case must be rendered directly as part of the publication.
- Siobhan is reading a comic and comments on a particular image that it is much darker than the other cells in the publication.
- Thomas is reading a white paper that includes an embedded dataset. He tags the dataset with a semantic URI identifying the subject matter of the dataset, which is different to the paper as a whole.
2.2.5 Annotating Parts of Embedded Resources
A user wishes to annotate a particular part of an embedded resource, such as a rectangular section of an image or a particular time range of an embedded video file. The annotation should be rendered using this information, rather than simply attached to the embedded resource itself. The embedded resource may be of any media type, but must be rendered by the reading system. Thus video, image, audio and similar are in scope for this use case, but not stylesheets or scripts which are not rendered directly. Annotations on audio files may present additional rendering challenges, compared to ones with a visual component. The user then wishes to share the annotation with others.
The parts of resources to be annotated include:
- Character position in an embedded text or data stream
- Time position within an audio or video stream
- x/y points in an area such as an image or video
- x/y/z points in a volume such as a 3d object
- Character ranges within a text or data stream
- Time ranges within an audio or video stream
- Areas within an image, including rectangular, circular and polygonal areas
- Volumes within a 3d object
- Umeko is teaching a class on physics and annotates part of an embedded video within the electronic textbook, delineating the time range that she wants to use as an example. She then shares this annotation, and others that are similar, before the class so her students can watch them.
- Vladimir is reading an online magazine about fashion and annotates part of one of the images that depicts a particular style he wishes to replicate in his own work.
2.2.6 Annotating Alt Text of Embedded Resources
A user wishes to write a comment about a resource embedded within the publication, and to associate it with alternate, accessible representations of that resource, such as the alt text/long desc provided. The comment may be only about part of the alternate representation, and thus segments of the alternate representation must be able to be selected. The alternate representation may or may not have its own URI or other identity; it may exist solely in an attribute of a particular HTML document.
- Whitney is concious of accessibility and annotates the depiction of a friend in a photograph, and wants to align that annotation with the name of the person in the textual description of the photograph in her school yearbook. The text description is provided in the alt text of the image element.
- Xavier is annotating a video. He associates his comments about linguistics with both the time range of the video, but also the accessible text transcription of the speeches.
2.2.7 Annotation Comparing Segments within a Publication
A user wishes to annotate two or more parts of a publication, embedded resources, or part of an embedded resource, in order to compare or contrast the targets. This may be to point out inconsistencies in the content or rendering, to make a note about two similar or related passages, or to link part of an embedded resource to where it is referenced in the text.
- Yadira is studying a book for an English class and highlights the sections where the author is talking about the age of a character, to demonstrate that the author is inconsistent. She makes the case in the comment that this is intentional.
- Zahir highlights areas in charts within a scientific article that demonstrate a particular fact related to his own work. He comments with a personal note to this effect.
2.2.8 Annotation Comparing Segments between Publications
A user wishes to annotate two or more parts of different publications in order to compare or contrast the targets. This may be to make a note about two similar or related passages such as plagiarism, or to link part of an embedded resource to where it is referenced elsewhere. For example, the user may wish to link appearances of the same character in multiple books, popular references to prior works, or examples of passages that contradict each other in scholarly literature.
- Ahmed discovers three news articles about the same event which give very different accounts. He selects the disagreeing numbers given in each, and comments that he believes the lowest of the three and gives his rationale.
- Bianca is linking the transcriptions of song lyrics, published in various anthologies, together based on obscure references to particular real world people. She tags the segments with the person's identity in Wikipedia.
2.3 Advanced Annotation Use Cases
2.3.1 Cross Format Annotations
A user wishes to annotate a digital publication in one format and have the annotation appear for different representations of the same resource. For example, an annotation created on an EPUB should also be rendered on the equivalent PDF or HTML page. The annotation can be either on the publication level, or anchored to a particular part of the text. Annotations on embedded resources (such as images) that are embedded without identity in alternate representations are not considered in scope, for example annotating a part of an image in an HTML page which is then embedded within the PDF representation of the page.
- Craig is reading a book on motorsports that is published both online and reproduced as a PDF. He publishes an annotation about a span of text in the HTML version, and expects that it will appear in his tablet based reading platform after synchronization, where the same article is a PDF.
- Dee reviews a scholarly article in a dedicated client on her computer, where the article is a print-ready PDF. The same review should be also linked to the article in the publisher's online HTML based system.
2.3.2 Cross Version Annotations
A user wishes to annotate part of a publication for which she has multiple editions, or that is updated regularly, and have those annotations persist between versions of the same publication. If the publisher provides a new version of a publication, known to happen silently at times for various reasons, then the annotations about the publication should be available on this new version rather than equally silently disappearing. As with any annotation that should be presented with more than just the resource it was created for, cross versioning allows for a wider audience and thus is a potential target for spammers.
- Enrique wishes to annotate the first line of Hamlet in such a way that it should appear on all of the copies of the play that the user has access to, rather than just the particular version that was open when the annotation was created.
- Faith is a teacher who wishes to annotate a text book in such as way that her annotations are visible to her students even though they do not have the exact same version, but instead have acquired it from different retailers.
This use case is particularly challenging to solve in environments in which identifiers for the work, rather than the particular version, do not exist.
2.3.3 Maintaining Annotation Style
A user wishes to associate a particular style with an annotation, either for the comment or the delineation of the target of the annotation. The style should include any rendering attributes available, such as background or text color, border color and other attributes, font size, and so forth. When colors or styles associated with annotations are meaningful to an individual, to a particular group, or just generally, a text label should be able to be associated with the annotation drawn from a list of terms (taxonomy) or free text, in order to assist with accessbility.
- Gerard draws a bounding box on an image of the night sky, and wishes to ensure that his client in the future will draw the box in bright green to stand out, and certainly not to draw it in the default black which would be unable to be seen.
- Hailee highlights parts of a non-fiction text in two colors that have meaning to her; red strikethrough is statements that she disagrees with, and green background is for statements that she does agree with. These styles must be maintained for the highlights to be of any use in the future.
2.3.4 Maintaining Annotation Layout
A user wishes for their annotations to be presented at a particular location on the page, such that the layout of the annotations doesn't interfere with the reading of the publication. For example, annotations could be styled as a particular height and width, and then put into the margins of the page or over top of other white space. Annotations could be visually ordered such that reading them in the presented order gave a better experience than reading them in the order of the targets within the publication. Thirdly, the layout could be used for organization of thoughts concerning the publication by moving all of the related annotations together spatially. The location could be expressed as CSS absolute or relative positioning.
- Ichiro is reading a fixed-layout work and positions his annotations above whitespace in the text with arrows to the character span that they refer to. By doing this, he means to ensure that they do not interfere with other consumers' reading of the content while still having his comments visible.
- Jacinta is a publisher and lays out the author's annotations on a novel in such a way that they aid the reader in understanding how the author was thinking about his characters. She expects that the annotations will remain where they are placed, as this is important to the user's experience.
2.3.5 Recording State of Changing, Online Resources
A user wishes to annotate the publication as it appears with dynamic resources in a particular state, or in terms of the web architecture, given a particular representation. Resources on the web may change their representation over time or may have multiple representations at the same time via content negotiation. The URI of the resource alone is thus not sufficient to determine the representation that was delivered to the annotator, and additional information such as the time of the request and the HTTP headers sent must be recorded.
- Ken annotates an online travel publication that is frequently updated with the latest information, such as the prices of hotel rooms and the quality of restaurants in the area. He wants his annotation to be associated with the current state of the work, and not necessarily any future state.
- Lynda is reading a book that dynamically embeds images via a service. The JPG format that is used by a particular publication is rendered with too high a compression level, and it is hard to understand compared to the original PNG format. She thus wishes to comment only on the JPG that it is hard to see, rather than on the PNG which shares the same negotiable URI.
2.3.6 Recording State of User Manipulated Resources
A user wishes to annotate a publication with embedded, dynamic resources. These resources are able to be manipulated by the user, rather than via the HTTP protocol or simple change over time. Some number of manipulations must be performed in order for the target of the annotation to be visible or understandable, regardless of the accuracy of the description of the target segment. The consuming user agent should then be able to reproduce these manipulations in order to allow a third party to see the resource as annotated.
- Maurice is studying a publication that embeds a 3 dimensional model of a protein structure that can be rotated, panned and zoomed. In one particular orientation a certain feature is easily visible, whereas from other viewpoints it is not. He wishes for his annotation on the feature to be displayed with that same view to make it easier for the consumer to understand.
- Nadia highlights some text in a page that is responsive to user interactions and preferences. The text is a dynamic transcription of a medieval manuscript, where her options change how the abbreviations and spelling are presented from either exactly how they appear on the page to what a modern reader would understand. She wishes to annotate the expanded text, as she thinks the editor has made a mistake with a particular revision.
This use case is particularly challenging to solve in the generic case rather than with media specific solutions.
2.3.7 Annotation has a Choice of Multiple, Dependent Bodies or Targets
A user wishes to annotate a publication or part thereof with multiple options for the body or target. The options are thus dependent on each other, and only one of the options should be displayed to the user. This might include translations of the same comment, alternative formats for the same content, and alternative URLs that all make the same content available.
- Owen speaks both Japanese and English, and wishes to provide translations of his comment in both languages. He teaches English as a foreign language in Japan, and his students should be able to choose whether to view it in one language or the other.
- Petra annotates a paper that is published in multiple locations, however the representations are identical. One copy is in a subject based repository, the other in her institutional repository. She wishes to explicitly link both of the targets to ensure her annotation can be presented along with at least one copy of the paper from the most convenient location to the consumer.
2.3.8 Annotation has Multiple, Dynamically Defined Targets
A user wishes to target segments of a resource that appear more than once in that resource, termed here a "repeated segment". The user does not necessarily know the exact number of times the repeated segment appears in the resource; the interpretation of the annotation is understood to be independent of the number of instances of the repeated segment.
- Quinn, a copy editor, creates an annotation proposing a correction to replace all instances of the string "pleaf'd" with the string "pleas'd". Essentially the annotation is proposing a search and replace operation of the sort ubiquitous in modern word processing systems.
- Romana, a manufacturer, wishes to annotate all products of a certain class in his products database with a note that these items will go on sale next week for 15% off for 2 weeks only.
There are usability implications with annotating dynamically defined segments, rather than specific enumerated segments. This could be used as an attack vector for spam or exploitation of user agent bugs by annoting common words on frequently visited URIs. For example, annotating "a" on the top million sites with an advertisement in the annotation's body.
2.3.9 Determination of Annotation Validity after Target is Modified
A user annotates a publication with a correction to the text. The publisher then acts upon this annotation to correct the mistake, or in the scholarly field potentially to retract the publication from the scientific record. After the correction has been made, the annotation no longer applies to the publication and hence should not be displayed. It may be important not to delete the annotation, such that the user gets credit in some system for reporting the correction. The system that maintains the annotation may not be connected to the system that publishes the publication, and hence might not be able to be updated.
- Solomon annotates a gaming manual with a correction as to which controls are needed to perform a particular move. The publisher re-issues a new copy of the manual after the correction has been made to avoid other users having the same frustration. Quinn's annotation should not appear on the new version.
- Teynika annotates a typo in how her name is spelt (two 'n's instead of one) in a book about the research in her field. Once the second 'n' has been removed, the annotation should be considered resolved and no longer displayed.
This use case is particularly challenging to solve in the generic case rather than within specific systems that understand the motivation of the annotation and when it has been resolved.
2.3.10 Determination of Annotation Validity for Embedded Resources
A user annotates an embedded resource, such as an image, which is used in several places within a publication. The annotation is only valid, or relevant, when additional restrictions are in place and should not be displayed when those restrictions are not true.
- Ulrich reads a publication in which the same headshot photograph is used for two different people and wants to annotate the photograph to say that it is wrong when used on page 1, but not have the annotation displayed when the photograph is used correctly on page 3.
- Veronica wishes to comment that a company logo should only be used in the header on every page, but nowhere else.
2.4 Annotation Publication
2.4.1 Sets of Annotations for a Publication
A publisher has one or more sets of annotations about a publication and wishes to supply those annotations along with the publication. Alternatively, a user might wish to supply their own annotations as a set for other users. These annotations could be comments by the author (in the same vein as DVD extras commentary), from famous readers, or simply pointers to related works. In an education setting, this functionality could be used to provide additional commentaries on a text book or other publication that are intended to assist the student in understanding the material. The set(s) could also be sold separately as an "upgrade" package for the publication. The order of the annotations may be important, for example to read the publication in chronological rather than narrative order, or by following the order of a class lectures rather than the order of the chapters in the text book. The metadata about the collection of annotations is also important, such as who packaged them together and for what purpose.
- Wesley works for a publishing house and has transformed the author's commentary on their steampunk novel into a set of annotations for sale. The company wishes to have them available as an add-on for customers that have already bought the novel, and also in a bundle for new sales.
- Xena is a PhD student studying a famous detective story set in London. She works out a walking route that takes the user through all of the locations in the book in an optimal fashion, which is not the same order as the narrative, and wants to publish her annotations about the locations in that sequence.
2.4.2 Persistence of Annotations
A user wishes to save the annotation that they have created in order to retrieve it later, regardless of whether it is finished or not. The Annotation should be given a unique and resolvable identifier. The user may wish to save the annotation in their own system, rather than the system which provides the resource being annotated. The user may equally wish to save the annotation in multiple systems. The annotation should persist in local storage if the user is offline, and be persisted globally once the connection is re-established. In the interim, a locally unique identifier should be assigned to the annotation. Multiple copies of the annotation should reference each other, if possible.
- Yasir writes an annotation about an astronomy publication and wants to save it both in his own system and remotely for others.
- Zoe writes an annotation about Greek mythology which becomes popular and is syndicated widely across many systems after its initial publication online. The syndicated copies refer back to the original source, which Xena uses for credit towards promotion.
2.4.3 User or System Initiated Transfers between Systems
Either the user or the system requests that all or some subset of annotations that are maintained be transferred to another system. If the user requests it, then it this enables an export functionality such that the user's annotations can be exported to another platform or device. If the system requests it, then this enables a synchronization functionality where the user's annotations will be maintained in multiple locations for ease of use and preservation, or aggregation for analysis. Both such cases should use the same mechanism.
- Anya has two devices that are on the same network. The devices are set to synchronize his annotations whenever they detect each other.
- Bob has written a lot of annotations on a plane trip while offline. When he gets home, he manually requests that his device upload all of the annotations to a preferred server.
2.4.4 Annotation (or Part) is not Published Openly
A user wishes to keep their annotations or personal notes private, or only share with a small group of people such as a reading group, academic research group or only with a set of friends in a social network. Even if the user wishes to keep their annotations private, the ability to transfer the annotations between devices is desirable, so that they be used regardless of the particular reading platform.
The user may also wish to keep only some aspect of the annotation private, for example the comment should be protected, while the annotation graph can be shared openly, or vice versa. Regular web based authentication and authorization structures should be used to enable this functionality in an online environment to ensure interoperability.
- Catherine publishes her annotation on the effects of a particular pharmaceutical product in an authenticated environment in which only her and her colleagues can see it.
- Doug publishes his annotation openly so that other systems can see the linkage between the resources, but the comment itself is protected by an authentication system and paywall.
2.4.5 Publication (or Part) is not Published Openly
A user wishes to annotate a resource the she has access to, but requires authentication and/or authorization to view or annotate. The annotation should not circumvent or allow the circumvention of this DRM, for example by reproducing the content of the target publication.
- Elana annotates a closed access journal article that she has access to while at university. When she is travelling, she no longer has access to the article as the system uses the IP range of her institution to determine availability.
- Frank works for the closed access journal publisher and is concerned that the annotation Elana made quotes some of the protected text, and if someone were to annotate the entire text, it would break their authorization model.
2.5 Accessibility and Internationalization
2.5.1 Using Annotation for Contributing Accessibility Information
An annotation provider (personal or retailer) wishes to provide annotations that give additional information about resources for the purposes of accessibility.
- Gabby annotates an image with an audio file that records her description of the image. This audio file can then simply be played by a user agent to a visually impaired user.
- Hadrien annotates the text transcription of a segment of video to the appropriate place in the video stream. The transcription can be displayed to someone unable to hear the audio part of the video, or when the user agent does not have sound capability.
2.5.2 Location of Annotations
Users need to easily become aware of and find highlights or annotations, particularly when using a screen reader, a small screen, or seeking sparse annotations in a lengthy work.
- Isabelle is reading a long work about warfare that is not heavily annotated. She wishes to skip ahead to the next interesting section, and thus needs to have some way to visualize the location of the annotations that others have made on the work.
- Jason is using a screen reader, and wishes to have the option to listen to the annotations when they are available or to skip past them. Whenever the system encounters an annotation it gives an audio clue that tapping the screen will prompt the device to pause reading to convey the content of the annotation.
2.5.3 Using Annotation for Contributing Internationalization Information
A user wishes to provide internationalization information for a document that they don't conrol, such as a translation for a particularly complex phrase, or whether automated translation systems should explicitly not translate a given phrase.
- Katelynn has implemented a machine translation system that generates reliable Dutch translations and has it scheduled to run on commonly updated English-language sites, before publishing to a well-known annotation server in the Netherlands.
- Luke is a scholar in Ancient Greek, and routinely provides translations for online texts when they have been transcribed from museum objects. He wishes to make his translations available to both the museums and anyone who visits their online exhibitions.
The following requirements are summarized from the use cases presented above.
2.6.1 Annotation Model
- Identity of Annotation
- Identity of Publication (or Target Resource)
- Identity of Comment (or Body Resource)
- Identity of Resources Embedded within the Publication
- Multiple Formats for Comment, including Structured Data
- Distinction between Tag and Comment, or other types of Body Resource
- Annotations without a Body Resource (Bookmark, Highlight)
- Metadata about the Annotation
- Ability to target a point within a Publication
- Ability to target a range of characters within a Publication's text
- Ability to target an Embedded Resource
- Ability to target a segment (point, range, area, volume) of an Embedded Resource
- Ability to target alternate accessibility representation of an Embedded Resource
- Ability to target multiple resources with a single Annotation
- Ability to provide multiple resources as the body of a single Annotation
- Ability to specify that only one of the resources is required or should be rendered
- Ability to specify that all of the resources are required or should be rendered, perhaps in a particular order
- Ability to associate style information with bodies and targets
- Ability to associate timestamps with bodies and targets to determine the appropriate representation
- Ability to associate HTTP request information with bodies and targets to determine the appropriate representation
- Ability to have robust annotations that reference the same work in different media types
- Ability to determine the validity of annotations in a dynamic environment
- Collection of annotations, where the annotations in the collection are ordered
- Metadata about the Collection of Annotations
- Discovery of Annotations Relevant to Publication
- Persistence of Annotations
- Service for Sharing Annotations, either with others or between platforms
- Management of Shared Annotations
- Authentication and Authorization in the Annotation ecosystem