ECMA376

ECMA-376 is the Ecma International standard that specifies the Office Open XML (OOXML) file formats used by Microsoft Office applications and other software. The specification defines the XML-based formats for word processing, spreadsheets, and presentations, and describes the packaging mechanism that stores document parts as ZIP archives. The formats are designed for interchange and long-term accessibility, enabling documents created by one application to be opened and processed by others that conform to the standard.

The ECMA-376 standard is published as a multi-part document. It covers the fundamental markup languages for Office applications (such as WordprocessingML, SpreadsheetML, and PresentationML), as well as the Open Packaging Conventions (OPC) that define how parts are organized and related within a single packaged file. Additional parts address compatibility, extensibility, and metadata.

In practice, ECMA-376 defines widely used file extensions such as .docx for Word documents, .xlsx for Excel workbooks, and .pptx for PowerPoint presentations. Macro-enabled variants exist (for example, .docm, .xlsm, .pptm) to include executable code when permitted by the application.

Relation to ISO: the OOXML formats standardized by ECMA-376 were standardized by ISO/IEC as ISO/IEC 29500, and subsequent updates have been published as part of ongoing international standardization and maintenance. ECMA-376 remains a foundational reference for the specifications of the Office Open XML formats and their interoperability within the OOXML ecosystem.