Microsoft has fundamentally changed Excel's cell structure after 40 years by allowing multiple values to occupy a single cell through new features including Lists, Arrays in Cells, and Nested Arrays. This breaks one of spreadsheet's oldest conventions and enables users to keep related data together whilst still being able to work with individual items separately—for example, multiple project owners can now remain in the same cell and be available for filtering, calculations, and analysis.

The feature is currently available in beta for Windows and Mac as an opt-in capability and should not yet be used in important workbooks. However, the change presents significant compatibility challenges: external software libraries (such as openpyxl, pandas, and calamine) and applications that import Excel data (including Google Sheets, LibreOffice, and CSV exporters) may require updates, and existing Excel features like PivotTables may need adjustment. Microsoft has not yet specified how the new data type will be represented in .xlsx XML format, and users may need to flatten multi-value cells to work with certain existing features.