Section 21 of 102
20. Units and Measurement
Stable section ID: S05-CON-007-SECTION-21 · 33 content blocks
BDL shall use dimensionally typed quantities.
A quantity shall contain:
numeric value;
unit;
physical dimension;
precision where relevant;
uncertainty where relevant;
measurement status;
source where relevant.
Examples:
length: 2400 mm;
force: 15 kN;
pressure: 550 kPa;
temperature: 21 °C;
thermal_resistance: 3.5 m2*K/W;
BDL shall support SI units as the universal internal reference system while permitting authorized regional display and input units.
A document may declare default display units:
units {
length: mm;
area: m2;
force: kN;
pressure: kPa;
}
- Explicit units shall override display defaults.
- Conversions shall preserve the original value and unit where required for traceability.
Dimensional analysis shall reject invalid expressions:
// Invalid:
total_length: 5 m + 2 kN;
Temperatures shall distinguish between absolute temperature and temperature difference where necessary.
Measured values may include uncertainty:
installed_offset: 2.4 mm ± 0.3 mm;
Ranges shall be represented explicitly:
operating_temperature: [-20 °C, 60 °C];