Microsoft has begun testing a version of Excel in which a single cell can hold more than one value.
The feature, covering Lists, Arrays in Cells and Nested Arrays, is available as an opt-in preview in the beta channels of Excel for Windows and Mac. It is not in general release.
Until now, related items had to be split across separate columns, parked in helper tables, or flattened into a text string. The new behaviour lets them sit together in one cell while each remains individually addressable for filtering, calculation and analysis.
Microsoft is entirely aware of what it is doing. “One of the oldest rules of spreadsheets: one cell, one value. No longer!” wrote Jake Armstrong, senior product manager for Excel.
“With lists, you can keep those values together in one cell while still working with each item individually,” Armstrong said.
He also counselled restraint. This is a preview feature and it “shouldn't be used in important workbooks until general availability”.
The caution is warranted, because a very large amount of software assumes the old rule. The Register notes that external libraries including openpyxl, pandas and calamine may need updating, and that PivotTables and similar features may require adjustment.
The exits are narrower still. CSV export, Google Sheets, LibreOffice and older Excel builds have no way to represent a cell containing several values.
The rule being retired is about forty years old.
It is worth pausing on what a cell was. A cell was a place with a value in it, and the address of the cell was the name of the value. That correspondence is the entire reason a spreadsheet is legible to anyone who did not build it.
Under the preview, an address no longer names a value. It names a container. Containers can nest, so an address names a container of containers.
This newspaper finds the change conceptually tidy. A grid whose squares may each contain a further grid is not a grid with a new feature. It is a grid made of grids, which is a spreadsheet made of spreadsheets, and there is no level at which this stops on its own.
The Department of Unnecessary Research has followed the consequence to its natural destination. If a cell may hold anything, including other cells, then a workbook could in principle be kept in cell A1, and the remaining columns retained for appearance.
The formats that cannot follow are the ones built around the old promise. A comma-separated file is a file in which the comma means the end of a value. Informed that a value may now contain several values, it has nothing to offer.
The grid is unchanged. Every square in it is now a room, and Microsoft advises against keeping anything important in one.