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OpenDocument Chart Document Format (ODC), Version 1.2, ISO 26300-1:2015

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name OpenDocument Chart Document Format (ODC), Version 1.2. Part of OASIS Open Document Format for Office Applications, Version 1.2 and the equivalent ISO 26300-1:2015.
Description

The OpenDocument Chart Document Format (ODC), Version 1.2 (given the short name ODF_chart_1_2 here) is a format for editable documents that are charts based on tables of data. It is one of several subtypes in the ODF family for particular content categories. This description relates to part 1 of the ODF 1.2 specification as published by OASIS and the equivalent ISO/IEC 26300-1:2015 specification. The standard specifies markup for charts using the ODF chart: namespace. Such charts are often embedded into ODF documents of other categories. The standard also allows for free-standing chart documents with the file extension .odc. This description focuses on the free-standing file format but, apart from the file signifiers, is largely applicable to embedded charts as well.

Although free-standing chart documents were certainly produced by early versions of OpenOffice and perhaps by its predecessors, it appears that, as of late 2015, current versions of Apache OpenOffice and LibreOffice, office suites that use ODF as the primary native format, do not generate free-standing chart documents. Rather, they use the markup defined in the chart: namespace to define charts that are embedded in spreadsheets, textual documents, or presentations. See Notes below for a brief explanation of the mechanism used.

The primary ODF markup used for charts is specified in the chart: namespace, with the <chart:chart> element as a container for a single chart. This <chart:chart> element contains elements in the chart: and table: namespaces defining chart labels, legend, and the data to be charted. The data may be stored in the document, or retrieved by reference to another source. The <chart:chart> element has an attribute chart:class that specifies the type of chart to be plotted. Charts typically incorporate elements and attributes from the table:, draw:, and svg: namespaces.

For free-standing documents, the ODF specification covers two physical forms for ODF documents, a flat form as a single XML file and a package form based on the ZIP_6_2_0 format. This description focuses on the more commonly used ZIP-based package format for ODF chart files, given the .odc file extension. Files using the same markup specification and package but with an extension of .otc are for use as chart document templates.

An ODF package can be recognized as a chart document in several ways. Externally, there are file extensions for two ways in which ODF chart documents may be used in graphics applications, as noted above. The primary internal indication is that the mandatory file named mimetype will contain one of the corresponding strings listed as File signifiers below. An additional way to recognize an ODF chart document is that the <office:body> element, a child of the root <office:document-content> element in content.xml has the child element <office:chart>.

See Notes in ODF Family for more information about the flat XML-only variant of ODF files. For a flat ODF chart file, the root <office:document> element has an office:mimetype attribute with one of the values listed below as File signifiers.

For details of the ZIP-based package for ODF_chart_1_2, see ODF_package_1_2. The typical files for a minimal chart document include: mimetype (one-line file containing only the string "application/vnd.oasis.opendocument.chart"; ./META-INF/manifest.xml (package manifest); content.xml (chart content); styles.xml (chart formatting). The package specification defines the form for the package manifest, and options for digital signatures, encryption, etc.

Apart from changes to the underlying package format, changes made to the markup for ODF charts between ODF versions 1.1 and 1.2 were limited to a few enhancements and one added chart type.

Production phase Can be used in any production phase. Particularly used for creating documents (initial state) and for editing and review (middle-state). Used in final-state contexts where dynamically generated charts based on current data are required. Charts may also be converted to an image format that is designed for final publication and not for convenient editing.
Relationship to other formats
    Subtype of ODF_Family, OpenDocument Format (ODF) Family, OASIS and ISO/IEC 26300
    Used by ODF_spreadsheet_1_2, OpenDocument Spreadsheet Document Format (ODS), Version 1.2, ISO 26300:2015
    Used by Other ODF document categories.
    Subtype of ODF_package_1_2, OpenDocument Package Format, ODF 1.2, ISO 26300-3:2015
    Subtype of ZIP_6_2_0, ZIP File Format, Version 6.2.0 (PKWARE). Various features of the ZIP File Format are not permitted in ODF.
    Contains META-INF/manifest.xml file. This manifest file is mandatory in all ODF packages.
    Has earlier version ODC 1.1, not described separately on this site.
    Defined via XML_1_0, XML (Extensible Markup Language) 1.0. A normative RELAX NG schema is part of the specification for ODF 1.2, which includes the specification for chart documents.

Local use Explanation of format description terms

LC experience or existing holdings  
LC preference  

Sustainability factors Explanation of format description terms

Disclosure International open standard. Developed and maintained by OASIS Open Document Format for Office Applications (OpenDocument) TC as part of the OpenDocument Format (ODF) 1.2 specification published by OASIS in 2011. Also approved as part of the equivalent ISO/IEC 26300-1:2015 by ISO/IEC JTC1/SC34.
    Documentation

Specifications from OASIS: Open Document Format for Office Applications (OpenDocument) Version 1.2. Specification for ODF 1.2 chart documents are found primarily in chapter 11 of Part 1 of the specification. Since charts may contain tables and graphics, chapters 9 and 10 also relevant. The technical specification is part of a normative RNG schema for primary component files for ODF documents..

The identical specification is published as ISO/IEC 26300-1:2015, Information technology -- Open Document Format for Office Applications (OpenDocument) v1.2 Part 1: OpenDocument Schema.

The ODF 1.2 specification is divided into three parts, with the bulk of the markup specification in Part 1: OpenDocument Schema. The package specification has been moved into a separate Part 3: Packages.

See ODF_Family for a listing of namespaces that can be incorporated into any ODF 1.1 or ODF 1.2 document and links to associated specifications.

Adoption

The compilers of this resource have found no evidence that current applications using ODF as a native format support the saving of free-standing chart files. As of October 2015, documentation for both Apache Open Office and LibreOffice states that the applications do not create such files. See Useful References below. The ODF_chart_1_2 markup however, is used widely to embed charts in other ODF document categories, particularly in spreadsheets. Comments welcome.

    Licensing and patents No concerns. See ODF_Family.
Transparency

The structure and text of an ODC file are all represented in XML and hence viewable without special tools, although XML-aware tools that can show the element hierarchy make viewing and interpretation more convenient. The most commonly used parts, elements, and attributes have recognizable names. Simple documents can be interpreted with very basic tools. However, interpreting the semantics of some elements and the correspondence of some elements and attributes to charting terminology or functionality will require not only understanding of the schema and the specification text, but familiarity with the associated terminology and functionality.

Self-documentation

As for other members of the ODF 1.2 family, ODF_chart_1_2 added support for metadata based on RDF (W3C's Resource Description Framework). As well as using RDF for metadata for the document package as a whole, RDF can be attached to elements within the document's content. The use of "custom" metadata as specified in ODF 1.1 is deprecated in ODF 1.2.

Pre-defined metadata elements for the document as a whole, stored in an <office:meta> element include:

  • From the Dublin core namespace, using the dc: prefix: Title, Creator (of most recent modification), Description, Subject, Date (last modified), Language
  • From the ODF specification, using the meta: prefix: Generator (creating software application), Keywords, Initial Creator, Creation Date and Time, Modification Date and Time, Print Date and Time, Document Template, Document Statistics (word count, page count, etc.),

The pre-defined elements are all optional and repeatable. However, applications are not required to update multiple occurrences in a specific way to reflect modifications to a document.

Also supported in both ODF 1.1 and ODF 1.2 is an XML structure for user-defined metadata, based on triplets of name, data type, and value.

External dependencies

Depends on features used. Chart documents in ODF_chart_1_2 format may include links to externally stored data.

Technical protection considerations Encryption is supported for files within an ODF 1.1 or ODF 1.2 package. In addition, an ODF package file may be encrypted during interchange or as part of DRM controlling distribution.

Quality and functionality factors Explanation of format description terms

Still Image
Normal rendering No special quality and functionality factors have been developed for chart diagrams.
Clarity (high image resolution) Scalable
Color maintenance ODF 1.2 uses the notation #rrggbb to specify colors. The specification does not mention ICC color profiles.
Support for vector graphics, including graphic effects and typography Specialized support for different types of charts based on tables of data, e.g., bar-chart, pie-chart, etc.
Support for multispectral bands Not applicable.
Functionality beyond normal rendering Support for dynamic regeneration from updated data.

File type signifiers Explanation of format description terms

Tag Value Note
Filename extension odc
.odc is the extension used for a free-standing ODF chart file.
Internet Media Type application/vnd.oasis.opendocument.chart
The MIME types for ODF_chart_1_2 are the same as for earlier versions
Magic numbers See note.  Magic numbers that apply to ODF document category subtypes incorporate the magic number for ZIP_PK, the string mimetype at position 30, and the MIME subtype string value at position 38.
Indicator for profile, level, version, etc. ASCII: office:version="1.2"
The four root elements used in the primary files in an ODF package all require an attribute that records the ODF version. This is the signifier that distinguishes ODF 1.2 packages from earlier versions. Documents without this attribute are assumed to be from version 1.1 or earlier.
Tag Value Note
Filename extension otc
The extension .otc is used for a chart document used as a template.
Internet Media Type application/vnd.oasis.opendocument.chart-template
 

Notes Explanation of format description terms

General

In addition to specifying the ODF_chart_1_2 free-standing chart document format, ODF 1.2 specifies how charts using the same markup can be embedded in spreadsheets, textual documents (see ODF_text_1_2), and presentations. The mechanism for embedding a chart within an ODF document is to generate an ODF object that is equivalent to a .odc file, store it within the ZIP-based package, and refer to it through a <draw:object> element. See OASIS OpenDocument Essentials: Chapter 8. Charts -- Charts are Objects for a fuller explanation and examples. Sample files created in LibreOffice 4.3 confirmed the use of this mechanism. The chart markup is in a named object folder that includes its own content.xml (with root element <office:document-content>), meta.xml, and styles.xml files. Comments welcome.

History

See ODF_package_1_2 for discussion of changes to ODF in general between versions 1.1 and 1.2. Changes to the markup for charts between versions 1.1 and 1.2 were primarily enhancements requested by implementers. Appendix G of the ODF 1.2 schema specification indicates that three new elements were added to the chart: namespace and a number of new attributes were added.

See ODF_family for more on the history ODF in general.


Format specifications Explanation of format description terms


Useful references

URLs


Last Updated: Tuesday, 29-Dec-2015 15:00:29 EST