SEP 20: Add timezone information to all document metadata timestamps

Going forward this will be automated but for the existing set of documents the transformation will have to be at best semi-automated ie, script aided but with manual checking.

This will take the form of an update to the datetime format used in the frontmatter of each document.


It seems daft to discard the timezone in which a document was authored. While every document has location information, including this also in the datetime object allows for this data to be machine readable and will allow for more robust portability in the future.

Dates and times could, for example, be localised when appropriate.