# Properties

## ID

A unique identifier for this structure element, used for referencing it from other elements or external sources.

- Source: ISO 32000 Section 14.7.2
- Related tags: Document

## Ref

Defines or references the lower-level PDF objects (content items) that represent the actual text or graphic content of this element.

- Source: ISO 32000 Section 14.7.2
- Related tags: Document

## A

An attribute dictionary providing additional layout or semantic attributes for this element. May reference a class map.

- Source: ISO 32000 Section 14.7.2
- Related tags: Document

## C

An array of class names associated with this element, which can link to further style or attribute definitions in a class map.

- Source: ISO 32000 Section 14.7.2
- Related tags: Document

## T

An optional text label or title for this structure element—can serve as a short descriptor (e.g., for a heading).

- Source: ISO 32000 Section 14.7.2
- Related tags: Document, Figure

## Lang

Identifies the primary language for the text in this element (e.g., 'en-US'), aiding in proper text processing and accessibility.

- Source: ISO 32000 Section 14.7.2
- Related tags: Document, Figure, Caption, Span, Code

## Alt

Provides alternative text describing the element’s content, primarily for accessibility (screen readers).

- Source: ISO 32000 Section 14.7.2
- Related tags: Document, Figure, Code, Span

## E

Contains expansion text used to clarify abbreviations, acronyms, or symbolic content within the element.

- Source: ISO 32000 Section 14.7.2
- Related tags: Document

## ActualText

Gives an exact text equivalent for non-textual or symbolic content, allowing screen readers to read it as plain text.

- Source: ISO 32000 Section 14.7.2
- Related tags: Document, Figure, RT, Span

## AF

An array of associated files or file specifications that relate to this structure element (e.g., attachments).

- Source: ISO 32000 Section 14.7.2
- Related tags: Document

## NS

Specifies a namespace identifier for custom attributes, enabling extensibility without conflicting with standard keys.

- Source: ISO 32000 Section 14.7.2
- Related tags: Document

## PhoneticAlphabet

Indicates the phonetic alphabet used for any phonetic text within the element (e.g., IPA).

- Source: ISO 32000 Section 14.7.2
- Related tags: Document

## Phoneme

Contains the phonemic representation of text for pronunciation guidance or linguistic analysis.

- Source: ISO 32000 Section 14.7.2
- Related tags: Document