Missing unit
A requirement that lacks clear or consistent units for values. Missing or inconsistent units can cause confusion and implementation errors. Always specify units and use them consistently across related requirements.
| Category | Description |
|---|---|
| Rule mapping (INCOSE) | R6 – COMMON UNITS OF MEASURE |
| Default weight | 7.5 |
| Terms to avoid | mm, seconds, volts, °C, km/hr |
Example 1: Missing unit
Unclear Requirement: The speed of the toy car in water should be 90.
Issue: The unit of measurement is missing. Is it 90 km/h, mph, or something else?
Clear Requirement: The speed of the toy car in water should be 90 km/h.
Example 2: Inconsistent unit context
Unclear Requirements: The fuel pump shall have a maximum volume of 1 liter. The fuel pump shall have a flow rate of 250 l/h.
Issue: The second requirement assumes the unit from the first. If read separately, the unit is unclear.
Clear Requirement: The fuel pump shall have a flow rate of 250 liters per hour (l/h).
Note: Each requirement must be complete and self-sufficient. Always specify units, even if they seem implied.