ISO/IEC 29500 defines Office Open XML in two conformance classes. Transitional is
what nearly every .docx file is: it keeps features from older formats such as
VML, and ISO/IEC 29500-4 describes them. Strict drops those features. Word has
read and written Strict documents since Word 2013, as “Strict Open XML Document”, but saves
Transitional by default.
Namespaces
Strict documents use other namespace URIs for the same element names:
| For | Transitional | Strict |
|---|---|---|
WordprocessingML (w) | http://schemas.openxmlformats.org/wordprocessingml/2006/main | http://purl.oclc.org/ooxml/wordprocessingml/main |
Relationships (r) | http://schemas.openxmlformats.org/officeDocument/2006/relationships | http://purl.oclc.org/ooxml/officeDocument/relationships |
DrawingML (a) | http://schemas.openxmlformats.org/drawingml/2006/main | http://purl.oclc.org/ooxml/drawingml/main |
Drawing placement (wp) | http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawing | http://purl.oclc.org/ooxml/drawingml/wordprocessingDrawing |
Pictures (pic) | http://schemas.openxmlformats.org/drawingml/2006/picture | http://purl.oclc.org/ooxml/drawingml/picture |
Math (m) | http://schemas.openxmlformats.org/officeDocument/2006/math | http://purl.oclc.org/ooxml/officeDocument/math |
| Extended properties | http://schemas.openxmlformats.org/officeDocument/2006/extended-properties | http://purl.oclc.org/ooxml/officeDocument/extendedProperties |
Relationship types have the same Strict form: for example
http://purl.oclc.org/ooxml/officeDocument/relationships/styles in place of
http://schemas.openxmlformats.org/officeDocument/2006/relationships/styles. The
content types of parts are the same in both.
Telling them apart
Check the namespace of the root element of the main part. The root of a Strict document
also has the attribute w:conformance="strict". A reader that matches only the
prefix w: and the Transitional URIs will not recognise a Strict file.
<w:document xmlns:w="http://purl.oclc.org/ooxml/wordprocessingml/main"
xmlns:r="http://purl.oclc.org/ooxml/officeDocument/relationships"
w:conformance="strict">
…
</w:document>Differences in WordprocessingML
| Item | Transitional | Strict |
|---|---|---|
Alignment, w:jc | left, right and others | start, end and others |
Indents, w:ind | w:left, w:right | w:start, w:end |
| On/off values | 0, 1, true, false, on, off | Boolean values only |
Percentages, for example table width w:type="pct" | Fiftieths of a percent: 5000 is 100% | A percentage value, such as 100% |
VML (w:pict) | Allowed | Not part of Strict |
Compatibility settings (w:compat) | All, including the many legacy elements in ISO/IEC 29500-4 | Only those in Part 1, and w:compatSetting |
These are the differences a reader meets most often; the Standard’s parts 1 and 4 have the full list. Which features a particular file uses still depends on the program that wrote it.
The explorer on this site treats both as one format: it maps the two sets of namespaces to the same names, accepts the different values, and reports which class the document claims.