ODT - OpenDocument Text

ODT is the text document of the OpenDocument Format, the open standard developed by the OASIS consortium and published as an ISO standard. It is the native format of LibreOffice Writer and Apache OpenOffice Writer, and it was designed from the start to be an implementable specification rather than a description of what one program happened to do. Several governments adopted it as their official document format for exactly that reason.

How an ODT stores a document

Structurally an ODT is very close to a DOCX: a ZIP archive containing XML. The text lives in content.xml, the styles in styles.xml, the metadata in meta.xml, and the pictures in a Pictures/ folder as ordinary image files. A mimetype entry is stored first and uncompressed so that a program can identify the file without unpacking it.

The differences are in the details of the markup rather than the packaging. OpenDocument keeps a cleaner separation between content and styling, and it uses a single vocabulary across its text, spreadsheet and presentation documents, so an ODT and an ODS are recognisably the same design.

Round-tripping between ODT and DOCX works, and both LibreOffice and recent versions of Word will do it, but it is not lossless in either direction. Complex layouts, some numbering schemes and tracked-change histories are where the two vocabularies fail to line up exactly.

What metadata an ODT carries

All of it sits in one readable place, meta.xml, which makes ODT the easiest of the office formats to inspect by hand.

The standard fields are dc:title, dc:subject, dc:description, dc:language, meta:keyword, and the Dublin Core dates dc:date for the last modification and meta:creation-date for the original. Authorship is split in two: meta:initial-creator names whoever started the document and dc:creator names whoever saved it last.

Then come the statistics, and they are as candid as Word's. meta:generator names the exact application build that wrote the file, down to the version string. meta:editing-cycles counts how many times the document has been opened and saved. meta:editing-duration records the accumulated editing time as an ISO duration such as PT2H14M. A meta:document-statistic element carries the page, word, character, paragraph, table and image counts in one go.

User-defined fields are supported too, so a document can carry arbitrary custom properties that a template or a workflow tool added and nobody has looked at since.

When to use ODT

Use ODT when you want an editable document in a format nobody owns — for public-sector work where an open standard is required, for long-term storage of editable text, and any time you would rather not depend on one vendor's roadmap.

Use DOCX instead when you are collaborating with people who work in Word all day; the format conversion is one more thing to go wrong in a review cycle. And as with any editable format, export to PDF before sending a document you consider finished, since ODT layout depends on the fonts installed on the reader's machine.