The Excel (.xlsx) Extensions to the Office Open XML SpreadsheetML File Format specifies extensions to the Office Open XML file formats described in [ISO/IEC29500-1:2011]. The extensions are specified using conventions provided by the Office Open XML file formats described in [ISO/IEC29500-3:2011]. The extensions are a collection of structures and parts in a container that specify appropriate content, which can include unstructured or semi-structured tables of numbers, text, or both numbers and text, equations or functions, external data connections (2), charts, and images. Content in such a container is typically organized in a grid-based layout, and often includes numeric data, structured data, and formulas.
Sections 1.7 and 2 of this specification are normative and can contain the terms MAY, SHOULD, MUST, MUST NOT, and SHOULD NOT as defined in RFC 2119. All other sections and examples in this specification are informative.