Expression Syntax
Reference for the quantity expression field in assembly components.
Expression Syntax
Quantity expressions go in a component’s Quantity field when building an assembly. They define how much of this product is consumed per one unit of assembly output.
An expression is either a number, a {variable} reference, or any arithmetic combination of the two.
Constants
A plain number. The unit is implied by the product’s base UOM.
| Expression | Meaning |
|---|---|
0.15 | 0.15 of the product’s base unit per assembly output unit |
12 | 12 units per output unit |
0.05 | 0.05 hours of labour per output unit (if product UOM is hr) |
Variables
Reference a variable by wrapping its name in curly braces. Type { in the quantity field to open the autocomplete picker — it lists every system and company variable, filtered as you type.
| Expression | Meaning |
|---|---|
{stud_spacing_m} | Use the current value of stud_spacing_m |
{render_thickness_mm} | Use the current value of render_thickness_mm |
{waste_factor} | Use the current value of waste_factor |
Variable names are always lowercase letters, numbers, and underscores — e.g. stud_spacing_m, not StudSpacing or stud-spacing.
Arithmetic
Combine constants and variables with +, -, *, /, and parentheses. Standard operator precedence applies.
| Expression | Meaning |
|---|---|
0.15 * (1 + {waste_factor}) | Base quantity inflated by the waste factor |
{render_thickness_mm} * {density} | Two variables multiplied (e.g. mass per area) |
0.05 * {coats} | Labour scaled by coat count |
12 / {coverage_rate} | Constant divided by a variable |
1 / {stud_spacing_m} | Studs per metre from a spacing input |
Tips
- Prefer expressions over inflated constants.
0.15 * (1 + {waste_factor})is clearer than0.165and lets the estimator adjust waste at apply-time without editing the assembly. - Reuse system variables where they exist (
waste_factor,coverage_rate, etc.) so other estimators recognise the input and assemblies share values. - Create a custom variable rather than hardcoding a project-specific number — do this from the Variables tab.
- Names matter for picker UX — see Tips and pitfalls.