PDF accessibility testing rules

All content must be tagged or marked as artifacts.

To ensure a PDF is fully accessible, every content element in the document must be either associated with a Tag element (to be presented by the screen reader) or an Artifact (to be ignored by the screen reader).

Custom defined tags must provide a mapping to one of the standard known tag types so that assistive technologies understand how to present the custom tag.

The role mapping functionality described above is not limited to a single mapping. Custom tags can be mapped to other custom tags. This can even occur multiple times, creating a chain of mappings. Eventually, the chain must end at one of the standard PDF tags so the screen reader knows how to process all of the custom tags in the chain.

For example:

<MyBoldText> maps to <StyleSpan>

A failure in this checkpoint means that the role mapping of custom tags described above has an issue where one custom tag <Tag1> is mapped to another custom tag <Tag2> , but <Tag2> is mapped to <Tag1> . This is called a circular mapping. Circular mappings are not limited to just two tags, so some circular mappings of tags could be even larger.

For accessibility, we need all custom tags to map to one of the PDF standard tags so the screen reader knows how to process and present all tagged content. Therefore, any circular mappings need to be eliminated.

Custom defined tags cannot use the same name as one of the standard tag types.

A failure in this checkpoint means that the role mapping of tags described above has an issue where one of the standard PDF tags such as <H1> , <P> , <Sect> or <Table> has been remapped.

Screen readers and other technologies understand how to correctly process each of the standard tags. Therefore it is important that Role Mapping entries in a PDF file do not try to confuse the screen readers.

All documents must have a defined title in the Document Properties that provides a short, descriptive summary of the document.

Table tags should follow the correct structure to ensure they can be presented correctly to the user using assistive technologies.

A failure in this checkpoint means that the document contains or more <Table> tags, but there is something wrong with the structure of the table.

Tables are complex tags that have other internal tags inside them to represent each row, and each cell. Some cells are header cells (usually the first row and/or first column) and other are data cells. Rows are represented by <TR> tags and will contain their own internal tags for header cells <TH> or data cells <TD>.

List tags should follow the correct structure to ensure they can be presented correctly to the user using assistive technologies.

A failure in this checkpoint means that the document contains or more <L> list tags, but there is something wrong with the structure of the list.

Lists are complex tags that have other internal tags inside them to represent each item in the list. These are called list items and represented by the <LI> tag. Each list item can contain a list label

<Lbl> tag to represent a bullet or number prefix followed by a list body <LBody> tag. The list body contains the text or other content associated with the list item.

A failure in this checkpoint means that the document contains or more <TOC> table of contents tags, but there is something wrong with the structure of those tags.

Table Of Contents are complex tags that have other internal tags inside them to represent each item in the TOC. These are called table of contents items and represented by the <TOCI> tag.

Ruby tags are used to represent specific structures in Japanese typography and will only be applicable to use in such documents.

Warichu tags are used to represent specific structures in Japanese typography and will only be applicable to use in such documents.A failure in this checkpoint means that the document contains or more <Warichu> table of contents tags, but there is something wrong with the structure of those tags.

The Unicode specification defines unique ID values for all characters in all known languages in the world.

A failure in this checkpoint means that there is some text data in the document that cannot be properly read by a screen reader or other assistive technology because it is missing its required Unicode values.

Typically, the fonts associated with the text in the document will provide all of the required Unicode information required in a PDF file. In some cases, the fonts may have missing or incorrect Unicode information for some or all of the characters defined in the font.

The primary language of the document must be set in the Document Properties. All tags will inherit this language but can specify a different language when required in a multi-language document.

A failure in this checkpoint means that at least one Figure or image in the document does not have an alternate text description provided.

Screen readers will read this description to user when a Figure tag is encountered in the document.

A failure in this checkpoint means that the document contains some headings, but does not include an H1 (heading level 1). This prevents the screen readers and other assistive technologies from providing the required.

To resolve this error, review the current headings in the document and edit the tags to ensure there is at least one H1 tag.

Numbered heading levels in descending sequence are skipped (Example: H3 follows directly after H1).

A failure in this checkpoint means that the document contains more than one numbered heading tags such as H1 or H2, but they do not follow the correct sequence.

For example, you cannot jump from an H1 to an H3 tag. If you only had these two tags, the typical solution would be to change the H3 to an H2.

Some examples:

Valid:

<H1>

<H2> (+1 level OK)

<H1>

<H3> (+1 level OK)

<H2> (+ 1 level OK)

<H4> (+1 level OK)

<H4> (+2 levels invalid!)

<H2> (-2 levels OK)

<H1> (-3 levels OK)

<H3> (+1 level OK)

<H3> (+2 levels invalid!)

<H1> (-3 levels OK)

To resolve this error, review the current headings in the document and edit the tags to ensure that they follow the correct sequence.

A failure in this checkpoint means that the document contains generic unnumbered heading tags ( <H> ) and they do not follow the required hierarchy in the tag tree.

The <H> tags can be used alternatively to numbered headings such as <H1> and <H2> , but they are not as common. Screen reader users can still navigate them easily, but may lose understanding of the document structure.

Specifically, this rule in PDF/UA-1 states that any node in the tag tree such as <Document> , <Div> , <Sect> cannot have more than one <H> tag. To address this you can use grouping tags such as <Div> or <Sect> to create sub structures that hold the H tags.

Some examples:

Valid:

<Document>

<H>

<Sect>

<H>

<Div>

<H>

There are no tags that have more than one direct child that is an H tag.

Invalid:

All H tags are direct children of the same tag (Document)

TIP

Using numbered headings instead of <H> tags can avoid this checkpoint and provide a better experience for screen reader users.

<Document>

<H>

<P>

<H>

<P>

<H>

A failure in this checkpoint means that there is not enough information in one or more <Table> structures to associate some table data cells ( <TD> ) with their corresponding table header cell(s).

Screen readers provide options for users to navigate table cells to understand the content they are interested in. They also provide the ability to read the table header cells for each TD cell as the user is navigating the table.

In the tagged PDF format, there are two options for Tables to define the relationships of TH and TD cells:

1. Setting the Scope property on the TH tag to be either Row or Column. Row scope means the TH cell is a header cell for all TD cells on the same row (positioned to the right of the TH). Column scope means the TH cell is a header cell for all TD cells in the same column (positioned below the TH).
2. Defining ID values for each TH, and then adding those TH IDs to any TD that is associated with the TH.

Using the scope option is suitable for simple tables with a single set of TH tags where either only the first row contains TH tags, or only the first column contains TH tags.

However, it is not uncommon for tables to be more complex and have multiple rows and/or columns that contain TH tags. In these instances, ID relationships are required.

A failure in this checkpoint means that the document contains one or more <Formula> tags but those tags do not have the required alternate text provided.

The <Formula> tag is used to encapsulate mathematical expressions. These could be simple expressions or highly complex expressions that use any combination of text, images and vector graphics to display expression on the page. Screen readers cannot automatically describe complex expressions; therefore, we must provide alternate text descriptions to explain the expression.

Documents that contain Optional Content elements that can be hidden or unhidden by the user during viewing must be structured correctly.

Some PDF files can consist of Optional Content that can be viewed or hidden by the authors or users who are viewing the PDF files. Examples can be CAD drawings, maps with multiple layers, or multi language documents where users can select which language to view the document in.

These PDF/UA checkpoints provide technical requirements on ensuring any optional content present in the document is configured correctly.

All embedded file attachments must provide a filename attribute.

A failure in this checkpoint means that the PDF file contains embedded file attachments, but the required filename property was not provided for some or all of those files. Screen readers can present this filename to describe the file attachments to the user.

A failure in this checkpoint means that the document contains interactive form elements in the XFA format that can modify the document layout dynamically. For example, the form may contain a button that adds additional rows of fillable text fields to an invoice when a user clicks on it. In some cases, this could add additional pages to the document as the number of rows increases.

To reduce complexity for accessibility users and tools such screen readers, these types of dynamic forms are not permitted by PDF/UA.

At the technical level, there are two types of interactive forms allowed in PDF: AcroForms and XFA. XFA was intended to provide more robust capabilities of PDF forms, but its requirements were overly complex and it did not receive wide adoption by PDF software tools beyond Adobe’s tools.

Additionally, in the PDF 2.0 specification (ISO 32000-2) the use of any XFA forms has been deprecated and going forward AcroForms will remain the only standard for PDF forms. Support for XFA will eventually be removed in all PDF creation software.

Annotation objects in the document are required to use the Annot tag if they are not one of the common annotation types: Form, Link or Print Marks.

A failure in this checkpoint means that there is an untagged PDF annotation object that is not one of the common types (interactive link, form field or printer mark). These types of annotations are required to be tagged using the <Annot> tag.

A failure in this checkpoint means that there is a PDF annotation object that is correctly tagged using the <Annot> tag type but the tag does not provide alternate text required for screen readers to describe the annotation.

A failure in this checkpoint means that there is a form field annotation object that is correctly tagged using the <Form> tag type but the tag does not provide alternate text required for screen readers to describe the form field.

A failure in this checkpoint means the PDF file contains an annotation object, but the type of annotation is not specified.

This is a very uncommon event as most PDF creation software will not omit this information. However, the PDF/UA specification includes this requirement to ensure all PDF files can be properly supported by assistive technologies.

A failure in this checkpoint means the PDF file contains a TrapNet type annotation object. These uncommon types of annotation objects are specialized for use in PDF print focused environments to provide quality control of printed documents.

Experience this failure is a very uncommon event as most PDF creation software will not include these types of artifacts unless they are intended for print production environments. However, the PDF/UA specification includes this requirement to ensure all content in a PDF file can be properly supported by assistive technologies.

A failure in this checkpoint means that there is an interactive form field annotation object that is using a tag other than <Form>.

All interactive links in the document must be tagged using the Link tag.

A failure in this checkpoint means that there is an interactive link annotation object that is using a tag other than <Link>.

A failure in this checkpoint means that there is an interactive link annotation object that does not provide a description of the link for screen reader users.

A failure in this checkpoint means that there is a media clip annotation object (such as a video or audio clip) embedded into the PDF file but that object does not provide any alternate text to describe the content of the media clip.

A failure in one of these checkpoints indicates that the PDF file contains a Type 0 font resource that does not properly define the visual glyphs and Unicode values for all characters defined in the font.

This could lead to incorrect viewing and screen reader presentation of the document.

A failure in one of these checkpoints indicates that the PDF file uses one or more fonts but only provides the name of the font; it does not provide the actual font file as an embedded resource.

When this occurs, the PDF viewing application must choose the appropriate substitute font from the set of fonts that are installed on the user’s system. This means the PDF file may not view consistently in all operating systems or environments.

A failure in one of these checkpoints indicates that one or more font files embedded in the PDF do not contain the correct set of visual glyphs to represent the text characters used by those fonts in the document.

When this occurs, the PDF may not display correctly on some or all platforms.

A failure in this checkpoint indicates that one or more fonts embedded in the PDF define characters widths that are inconsistent with how the PDF file positions text on the page.

This requirement in PDF/UA is intended to ensure that PDF files view consistently on all platforms by all software applications.