This moves a document's abstract from the main text into the metadata. Metadata elements usually allow for finer placement control in the final output, but writing body text is easier and more natural.

A document abstract can either be put directly in the document metadata, for example by inserting an abstract attribute into a YAML block.

---
abstract: |
  Place abstract here.

  Multiple paragraphs are possible.
---

The additional indentation and formatting requirements in YAML headers can be confusing or annoying for authors. It is hence preferable to allow abstracts be written as normal sections.

# Abstract

Place abstract here.

Multiple paragraphs are possible.

This filter turns the latter into the former by looking for a top-level header whose ID is abstract. Pandoc auto-creates IDs based on header contents, so a header titled Abstract will satisfy this condition.^[1]

[1]: This requires the auto_identifier extension. It is enabled by default.

The abstract can be placed anywhere in the document.

The filter assumes that the abstract runs up until the next heading or horizontal rule, whichever comes first. Thus the abstract can be placed at the beginning of a document whose text doesn't start with a heading:

# Abstract

The abstract text includes this.

* * * *

This text is the beginning of the document.