Building Definition Language

BDL Dimensions shall express controlled geometric quantities between defined geometric features or datums.

Dimension types shall include:

linear;

angular;

radial;

diameter;

arc length;

elevation;

offset;

spacing;

thickness;

clearance;

depth;

area;

volume.

Every Dimension shall identify:

Dimension ID;

measured or controlled features;

nominal value;

unit;

tolerance;

dimension role;

source;

status;

evidence where measured.

Dimension roles shall include:

driving;

reference;

derived;

measured;

minimum;

maximum;

preferred.

Example:

dimension Beam_B01_Length {

from: @Beam_B01.End_Datum_A;

to: @Beam_B01.End_Datum_B;

nominal: 3600 mm;

tolerance: ±1.5 mm;

role: driving;

}

A derived dimension shall identify its expression:

dimension Room_Area {

value: @Room.width * @Room.length;

role: derived;

}

Conflicting driving dimensions shall generate a validation error.

Dimension chains shall identify the controlling datum strategy. BDL shall support tolerance-stack analysis but shall not assume that every chain dimension may vary independently.