Excel Support

Implicit conversions between numbers, text, booleans, and errors as Excel applies them inside formulas — e.g. "3"+2, TRUE*5, comparing dates with text, and propagating #N/A through arithmetic.

NOW, TODAY, RAND, RANDBETWEEN, RANDARRAY, OFFSET, INDIRECT, INFO, CELL — functions whose output is not a pure function of inputs. Coverage exercises Explo's deterministic, reproducible, and non-deterministic execution modes.

Excel intentionally treats 1900 as a leap year for Lotus-1-2-3 compatibility. Coverage ensures Explo's date arithmetic reproduces the off-by-one for dates on or before 1900-03-01.

Behaviors that diverge across Excel for Windows, Mac, and Web — locale-bound parsing, rendering of certain glyphs, and platform-specific functions like PHONETIC.

Workbooks using the 1904 date base instead of the default 1900 base. Coverage ensures dates render and compute correctly under both systems.

Spilling output from SEQUENCE / UNIQUE / SORT / FILTER / dynamic LET, including how spill ranges interact with downstream formulas, dependency tracking, and #SPILL! errors.

Cycles in the dependency graph. Explo detects them via strongly connected components and emits the workbook's saved baseline value for cells inside a cycle (no iterative-calc convergence yet).

Pre-dynamic-array @ semantics — using a multi-cell range where a single value is expected, including legacy formulas that relied on the row/column intersection rule.

Ctrl+Shift+Enter array formulas — the pre-dynamic-array way of producing array results, still authoritative in workbooks authored before Microsoft 365.

Workbook- and sheet-scoped defined names, including names that reference single cells, ranges, constants, and other names.

Sheet2!A1-style references resolving across sheets within a workbook, including references that survive sheet renames and reorders.

Table[Column], Table[#All], Table[#Headers], Table[@Column] — the Table-aware reference syntax that resolves to ranges at evaluation time.

Sheet1:Sheet3!A1-style ranges that span multiple sheets, including aggregate functions (SUM, AVERAGE, COUNT) operating across the 3D range.

Native Excel Tables — auto-expanding ranges, total rows, calculated columns, and references that follow row inserts/deletes.

Workbooks containing VBA modules. Coverage ensures the workbook is accepted, parsed, and evaluated correctly even when VBA is present; macro execution itself is not supported yet.

IEEE-754 rounding behavior under operations where it matters — accumulating long sums, transcendentals (LN, EXP, trig), and financial functions whose results depend on iterative algorithms.