Sub
| Description | Specifies subscript text, used in expressions like mathematical formulas or chemical notations where text is set below the baseline. |
|---|---|
| Namespace | 2.0 |
| Category | 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.
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 'Sub' element is used to denote subscript text in Well-Tagged PDF. It indicates that the enclosed text should be rendered lower than the baseline, typically for scientific, mathematical, or chemical notations.
It must be properly nested within the inline structure and should clearly convey its role as subscript, ensuring that content extraction and reflow processes recognize the altered baseline.
PDFUA:
In PDF/UA, the 'Sub' element signifies subscript text, which is important for accurately representing content like formulas or annotations in an accessible manner.
Each 'Sub' element must be tagged so that assistive technologies can interpret it correctly, preserving the semantic relationship between the subscript and its associated content.
Use cases
Sub element used to identify lines in document
Try itSub elements represent individual lines of code.
Try itTag Relationships
Click on any tag to view its details.