Glossary
These terms describe workbook data, calculation, and the layers that expose the engine. For a first walkthrough, read Basic concepts.
Packages and settings
| Term | Meaning | Details |
|---|---|---|
| Headless | Runs without a spreadsheet application's user interface | Why Formulon |
| Runtime | The environment running the application, such as a browser or Node process | Runtimes |
| Surface | A host-facing API and distribution format, such as WASM, Python, or CLI | Choose a surface |
| Binding | Code that exposes the shared core to a host language | Bindings |
| Excel compatibility profile | Runtime rules for the Excel platform and locale being modeled, such as mac-365-ja_JP; not saved in the workbook | Locale profiles |
| UI locale | The language of Cell's controls; a mounted locale change also coordinates its workbook profile | Language switching |
| UI profile | A Cell configuration such as embedded or full that chooses controls and features | Options |
| Invariant formula | Stored formula text using common English function names and separators, independent of displayed locale | Formula language |
Cells and calculation
| Term | Meaning | Details |
|---|---|---|
| Workbook model | The in-memory sheets, cells, formulas, styles, and calculation state loaded from a file or created by the host | Lifecycle |
| A1 address | A cell or range name such as Summary!B2; numeric API indexes start at zero instead | Basic concepts |
| Cached value | A formula's stored result; it may be stale until recalculation | Recalculation |
| Display text | The string obtained by formatting a value, distinct from the raw value and formula text | Presentation |
| Dirty cell | A cell whose calculated value needs refreshing | Recalculation |
| Precedents | Cells a formula reads: A1 is a precedent of B1 when B1 contains =A1*2 | Dependency tracing |
| Dependents | Formula cells that read a cell: B1 is a dependent of A1 in that example | Dependency tracing |
| Dependency graph | The relationships used to determine which formulas need recalculation and in which order | Recalculation |
| Volatile function | A function reevaluated on recalculation even without an input edit, such as NOW or RAND | Recalculation |
| Spill / anchor | An array formula's output area / the cell containing that formula | Dynamic arrays |
| Partial recalculation | Refreshes requested output cells and the formulas they need; other dirty cells may remain pending | Recalculation |
Files and tools
| Term | Meaning | Details |
|---|---|---|
| Round trip | Load a workbook and save it again; preservation does not imply rendering or evaluation of every feature | File formats |
| Passthrough | File parts retained as bytes rather than interpreted by the workbook model | File formats |
| Loss diagnostics | Reports of file features skipped, deferred, or dropped during reading or writing | File format support |
| Pivot cache | The stored source records and items a PivotTable summarizes; recalculation does not refresh the cache from its source | PivotTables |
| Oracle data | Reference results captured from real Excel for compatibility checks | Oracle testing |
| MCP session | One open workbook held by the local MCP server and addressed by sessionId; saving writes it to a file | MCP workflow |
| Session dirty flag | Indicates that a session may differ from its last successful lossless save; distinct from calculation dirtiness | MCP workflow |