07.3 · Formula Engine

Variable and Line References

Formulas refer to other cells and values using one of three syntaxes.

1. Line References (other rows)

Syntax	Meaning
`L10`	Line 10's default value (typically Total).
`#lq10`	Line 10 Quantity.
`#lt10`	Line 10 Total.
`#lr10`	Line 10 Rate.
`L1:L10`	Range of lines (used directly = sum; used in `SUM()` = list).
`2:10`	Shorthand range (defaults to total).

Range Behaviour

A bare range like L1:L10 in an arithmetic expression is implicitly summed:

= L1:L10                    → Σ totals from L1 through L10
= SUM(L1:L10)               → same thing, explicit
= AVERAGE(L1:L10)           → average
= MAX(L1:L10) - MIN(L1:L10) → range span

Breakdown vs Main Grid

Inside a breakdown's formula context, L# refers to breakdown lines, not main grid rows. To reach the parent item's value from a breakdown, use its Project parametric or pass data via a custom column.

2. Variable References (defines)

Syntax	Meaning
`#variable_name`	Standard reference, case-insensitive.
`[VARIABLE_NAME]`	Alternate bracket syntax.

Rules:

Starts with a letter.
Contains letters, digits, underscores.
Case-insensitive (#rate, #Rate, #RATE all point to the same define).

Examples:

= #floor_area * 1.1
= [LABOUR_RATE] * 40

The resolution order is:

Local scoped parametric (this breakdown).
Parent scoped parametric (e.g. item-level).
Global project define.
Live-computed defines (see 07.5).

If none matches, #NAME? is returned.

3. Custom Column References

Syntax	Meaning
`#cc.ColumnName`	Value of the custom column on this row.

Plus the aggregate family covered in 07.8: SUMCC, AVGCC, MINCC, MAXCC, COUNTCC, SUMIFCC, COUNTIFCC, AVGIFCC.

Line Numbers Are Stable

The LineNumber column is auto-maintained. If you insert a row between L5 and L6, TX1:

Re-sequences line numbers.
Rewrites any formula referencing affected lines (L7 + L8 becomes L8 + L9).

This means your formulas survive inserts and deletes without manual fix-up.

Watch Out

Deleting a referenced line leaves #REF in the formula — TX1 doesn't delete rows that are referenced without asking first.
Renaming a project parametric updates all formulas automatically (the rename propagates via the dependency graph).