On iPhone Metadata keys can be used as variables in text, and they will be automatically substituted for Export and in Preview.
One of the best uses of metadata, for example, would be to build correspondence templates.
Document Metadata
Writer supports metadata at the beginning of documents.
Metadata must be separated from the rest of the document by three dashes.
To do so, define your metadata at the
very top of your document, followed by an empty line.
---
Customer: M. Bluth
Me: Bob Loblaw
Date: April 3rd, 2023
---
You can then use the metadata in the text by putting it in [brackets] and adding a % sign.
Sincerely,
[%me]
Global Metadata
Metadata that applies to every file can be defined in Markdown settings.
Global metadata has the lowest priority, so that a document that explicitly specifies its author will always use that value when a variable is used.
Content Block Metadata
Content Block metadata is placed immediately after a
Content Block. This metadata has the highest priority.
They are optionally enclosed with three dashes.
Letter.text
Name: John Smith
Date: January 2
Images support title, alt, width, and height attributes:
Image.png
Title: Pie Chart
Alt: Pie chart with 2 slices: a 50% slice called “left”, and a 50% slice called “right”
Width: 50%
Metadata 
