Multi-sheet workbooks

:sheets                    Interactive picker: list sheets, select one to switch
:sheet                     List sheets inline (active marked *)
:sheet Inputs              Switch by name
:sheet 1                   Switch by zero-based index
:sheet add Outputs         Append (does not switch)
:sheet del Tmp             Remove (refused if last sheet)
:sheet rename Old New      Rename, rewriting `Old!` prefixes in formulas
:sheet move Inputs 0       Reorder

A workbook with more than one sheet shows a tab strip on the bottom line (active tab highlighted, with an i/n position counter); single-sheet workbooks leave that line clear. The status bar also prefixes the active sheet name (Inputs!A1) whenever a workbook has multiple sheets.

Cross-sheet references

Reference cells on other sheets with Sheet!cell:

=Sheet2!A1
=SUM(Sheet2!A1:A10)
=Sheet1!A1 + Sheet2!B1

Quote a name that is not a plain identifier -- one containing spaces or punctuation -- and double the apostrophe to include one:

='My Sheet'!A1
=SUM('Q1 Results'!A1:A10)
='It''s'!B2

The dependency graph is keyed on (sheet, col, row), so cross-sheet recalculation works transparently.

Inserting, deleting or swapping rows and columns moves only the references that resolve against the edited sheet. A formula on another sheet that names this one follows the edit; one on this sheet that names another is left alone, because that sheet's lines did not move.

Cross-sheet ranges (Sheet1!A1:Sheet2!B5) are not supported. Neither does Excel, and they would defeat the static dependency analysis -- see Limitations.