Formula
| Description | Encapsulates mathematical expressions or equations, preserving the semantics of technical or scientific formulas. |
|---|---|
| Namespace | 1.7 2.0 |
| Category | grouping block inline |
Attributes
Specifies how the element is placed relative to surrounding content (e.g., block-level or inline flow).
Defines the direction of text flow (e.g., left-to-right, right-to-left, or vertical).
Sets the background color for the element’s content area.
Specifies the color of the border around the element.
Indicates the style of the border (e.g., solid, dashed, dotted).
Defines the thickness of the border line in user space units (such as points).
Determines the space between the element’s border (or boundary) and its inner content.
Applies the primary color (fill or stroke) for the text or graphic content.
Declares an explicit width for the element in user space units.
Declares an explicit height for the element in user space units.
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 'Formula' element in Well-Tagged PDF represents mathematical expressions or equations within a document, ensuring that they are distinctly identified.
It should include notations or metadata to indicate that the enclosed content is a formula, thereby supporting accurate reflow and extraction of technical content.
PDFUA:
In PDF/UA, the 'Formula' element makes mathematical content accessible by providing semantic cues and, where necessary, alternative text descriptions for complex expressions.
Formulas must be tagged with additional metadata or alternate representations to ensure that assistive technologies can convey their meaning correctly.
Use cases
Simple formula represented by textual content
Try itChemical formula represented by textual content and layout attributes
Try itFormula represented with MathML substructure
Try itTag Relationships
Permitted Parent Tags
Permitted Child Tags
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Related Matterhorn Protocol checkpoints
- Tags are not in logical reading order.
- Structure elements are nested in a semantically inappropriate manner. (e.g. a table inside a heading).
- The structure type (after applying any role-mapping as necessary) of a structure element is not semantically appropriate.
- Content is a mathematical expression but is not tagged with a Formula tag.
- Formula tag is missing an Alt attribute.
- Unicode mapping requirements are not met.