Development/ODF Implementer Notes

    From The Document Foundation Wiki

    This page concerns ODF-specific Implementer Notes for LibreOffice and DLP developers.

    For more general information about the format, see the ODF page.

    ODF Technical Events

    LibreOffice participates in ODF Plugfests hosted by the OpenDoc Society:

    ODF Extensions

    ODF Version Choice

    In the code, look for ODFVER_* enum values - currently, there is ODFVER_UNKNOWN, ODFVER_010, ODFVER_011, ODFVER_012, ODFVER_012_EXT_COMPAT, ODFVER_012_EXTENDED, ODFVER_013 and ODFVER_LATEST (this means ODF 1.3 Extended at the moment).

    ODFSVER_012_EXT_COMPAT should be used to fallback to old, incorrect output - we e.g. use that to write svg:d path statements that are interpreted wrongly by buggy legacy ODF consumers.

    The difference between ODFSaneDefaultVersion and ODFDefaultVersion enums is that ODFSaneDefaultVersion provides enums that can be used in exact comparisons and the "plain" ODF version is smaller than the same version with extensions allowed and if extensions are allowed the ODFSVER_EXTENDED bit is set and SvtSaveOptions::GetODFSaneDefaultVersion() returns always a specific ODF version, whereas ODFDefaultVersion::ODFVER_LATEST is a running target meaning always the latest and greatest that you don't know which it actually is.

    Manually exported elements and attributes

    If you implemented a feature that needs to extend ODF - please use the following pattern:

     // export only if ODF extensions are enabled
     if (rExport.getSaneDefaultVersion() & SvtSaveOptions::ODFSVER_EXTENDED)

    Obtained through SvXMLExport::getSaneDefaultVersion() (don't call SvtSaveOptions::GetODFSaneDefaultVersion() directly because there could be an override in SvXMLExport), this is how features that are already part of a Committee Specification Draft at OASIS can be exported:

    SvtSaveOptions::ODFSaneDefaultVersion eVersion = rExport.getSaneDefaultVersion();
    if (eVersion >= SvtSaveOptions::ODFSVER_013)
        ... write ODF 1.3 namespace etc. ...
    else if ((eVersion & SvtSaveOptions::ODFSVER_EXTENDED) != 0)
        ... write extension namespace etc. ...
    // else, version is < 1.3 and extensions are not allowed, the feature is not saved.

    Another way to express "save only if 1.2 extended or in next version 1.3 or later" with SvXMLExport& rExport would be

    // Export only for 1.2 with extensions or 1.3 and later.
    SvtSaveOptions::ODFSaneDefaultVersion eVersion = rExport.getSaneDefaultVersion();
    if (eVersion > SvtSaveOptions::ODFSVER_012)
        // For 1.2+ use loext namespace, for 1.3 use number namespace.
                ((eVersion < SvtSaveOptions::ODFSVER_013) ? XML_NAMESPACE_LO_EXT : XML_NAMESPACE_NUMBER),
                XML_your_feature, aString );

    Extension namespaces

    Elements and attributes that are not defined in an ODF specification yet, even if already submitted as a proposal to the OASIS ODF-TC, have to be written with an extension namespace, otherwise validators will complain about invalid elements or attributes. For example, instead of text:new-attribute it needs to be loext:new-attribute. There are predefined extension namespaces available, the only one that should be used for new features is XML_NAMESPACE_LO_EXT that maps to the loext of the example, which you would use instead of XML_NAMESPACE_TEXT. (See XML_NAMESPACE_EXT in include/xmloff/xmlnmspe.hxx for definitions of namespaces)

    In the ODF reader prepare to import both namespaces, in this example the loext that is written and the proposed future namespace, here text. If you don't do this then the current version will not be able to read documents that use the proposed attribute once it was accepted by the OASIS ODF-TC. For example by using

    if (nPrefix == XML_NAMESPACE_LO_EXT || nPrefix == XML_NAMESPACE_TEXT)

    or in an import (!) property map have two SvXMLTokenMapEntry


    SvXMLExportPropertyMapper, Extensions in XMLPropertyMapEntry arrays

    You may find yourself adding a new feature to an array that maps between UNO properties and XML attributes.

    Typically you need to add 2 entries, one with LO_EXT namespace and SvtSaveOptions::ODFSVER_FUTURE_EXTENDED version, and the other with some OASIS namespace and SvtSaveOptions::ODFSVER_FUTURE_EXTENDED version; since LO 7.0, the mbImportOnly flag (the last member) doesn't matter in this case. This means that on export the LO_EXT attribute will be ignored in strict ODF versions and exported if the ODFSVER_EXTENDED bit is set, the OASIS namespace attribute will always be ignored on export, and both attributes will be imported.

    When the extended attribute is accepted into an ODF Committee Specification Draft, the version of both entries can be changed to the corresponding ODFSVER_xyz value and any mbImportOnly flag removed; this will prevent export of the LO_EXT attribute starting from this version, and enable export of the OASIS namespace attribute starting from this version.

    LibreOffice ODF extensions

    LibreOffice OpenFormula extensions

    ODF "implementation-defined" items in LibreOffice


    A (somewhat outdated) overview of the config-items supported by LibreOffice can be found in the spreadsheet in core.git at xmloff/documentation/LibreOffice_settings.xml_config-items.fods