Reference

Description	Denotes a cross-reference element that links to related content within the document or to external sources for additional information.
Namespace	1.7
Category	inline

Attributes

Placement

Specifies how the element is placed relative to surrounding content (e.g., block-level or inline flow).

WritingMode

Defines the direction of text flow (e.g., left-to-right, right-to-left, or vertical).

BackgroundColor

Sets the background color for the element’s content area.

BorderColor

Specifies the color of the border around the element.

BorderStyle

Indicates the style of the border (e.g., solid, dashed, dotted).

BorderThickness

Defines the thickness of the border line in user space units (such as points).

Padding

Determines the space between the element’s border (or boundary) and its inner content.

Color

Applies the primary color (fill or stroke) for the text or graphic content.

role

Main indicator of type. This semantic association allows tools to present and support interaction with the object in a manner that is consistent with user expectations about other objects of that type.

Differences

Well tagged PDF:

The 'Reference' element in Well-Tagged PDF is used for citations and cross-references within a document. It links text to bibliographic entries or external resources.

It should be clearly defined and associated with the related bibliographic or external content, maintaining a coherent structure for content extraction.

PDFUA:

In PDF/UA, the 'Reference' element enhances accessibility by providing clear navigational cues to cited materials or related content.

References must be tagged with descriptive metadata and linked accurately within the structure tree to facilitate navigation by assistive technologies.