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 [RFC2119]. All other sections and examples in this specification are informative.