The description of the elements of LDT luminaire files can be found in the following table:
Pos. | Description | designated number of digits |
| 1 | Manufacturer name / database / version / format identification | max. 78 |
| 2 | Type indicator Itype Ityp= 1 ... point rotation-symmertically luminaire ......= 2 ... line scource luminaire = 3 ... non point rotation-symmertically luminaire (only luminaires with characterisation Ityp = 2 are divisible in longitudinal and cross direction | 1
|
| 3 | Symmetry indicator Isym Isym = 0 ... no symmetry = 1 ... symmetry = 2 ... symmetry plane C0-C180 = 3 ... symmetry plane C90-C270 = 4 ... symmetry plane C0-C180 and plane C90-C270 | 1
|
| 4 | Number Mc of C-planes for 0 ... 360° (usual 24 for interior luminaires, 36 for street luminaires) | 2 |
| 5 | Distance Dc between C-planes (Dc = 0 für nicht gleichabständig vorliegende C-Ebenen) | 5 |
| 6 | Number of Ng of the luminous intensities in every C-level (usual 19, 37 or 73) | 2 |
| 7 | Distance Dg between the luminous intensities each C-level (Dg = 0 for luminous intensities being not of the same distance in the C-levels | 5 |
| 8 | Number of test certificate | max. 78 |
| 9 | Luminaire name | max. 78 |
| 10 | Luminaire number | max. 78 |
| 11 | File name | 8 |
| 12 | Date/person responsible | max. 78 |
| 13 | Length/diameter of the luminaire | (mm) 4 |
| 14 | Width b of the luminaire (b – 0 for circular luminaires) | (mm) 4 |
| 15 | Height of the luminaire | (mm) 4 |
| 16 | Length/diameter of the luminous area | (mm) 4 |
| 17 | Width b1 of the luminous area (b1 = 0 for a circular luminous area of the luminaire) | (mm) 4 |
| 18 | Height of the luminous area C0 | (mm) 4 |
19 | Height of the luminous area C90 | (mm) 4 |
| 20 | Height of the luminous area C180 | (mm) 4 |
| 21 | Height of the luminous area C270 | (mm) 4 |
| 22 | Ratio of the downward flux phi | (%) 4 |
| 23 | Light output ration of the luminaire EtaLB | (%) 4 |
| 24 | Conversation factor for luminous intensity | 6 |
| 25 | Tilt of the luminaire during measurement (important for street luminaires) | 6 |
| 26 | Number of equipment (optional) | n 4 |
26 a | Number of lamps | n * 4 |
26b | Type of the lamp | n *24 |
26c | Total luminous flux of lamps | (lm) n *12 |
26d | Colour temperature of the lamp | n *16 |
26e | Colour rendering index | n * 6 |
26f | Total system power | (W) n * 8 |
| 27 | Ratio of total luminous flux half-space for k = 0.6 ... 5 (for determination of number of lamps to light output ratio procedure LITG 5th edition 1988) | 10 * 7 |
| 28 | Angle C (starting with 0°) | Mc * 6 |
| 29 | Angle G (starting with 0°) | Ng * 6 |
| 30 | Distribution of luminous intensity (cd/klm) (Mc2-Mc1+1) for Isym = 0 is Mc1 = 1 and Mc2 = Mc for Isym = 1 is Mc1 = 1 and Mc2 = 1 for Isym = 2 is Mc1 = 1 and Mc2 =Mc/2+1 for Isym = 3 is Mc1 = 3*Mc/4+1 and Mc2 =Mc1+Mc/2 for Isym = 4 is Mc1 = 1 and Mc2 = Mc/4+1 | * Ng * 6 |
The prevised place number only serves for the estimation of the possible memory requirement on the mass memories. Every data element is saved as ASCII-string and equipped with an EOS-symbol.
The data format described here serves for the Lighting fixture data exchange provided that lighting fixture and dataset are assigned doubtlessly. In case nevertheless lighting fixtures with the same relative radiant caracteristics shall be combined in one file which dispose of different dimensions, efficience degree and fittings, in the corresponding positions there can be filed various data elements, separated by one space key each with the prevised place number. Correspondingly it is possible to save direct utilized flux shares, too, for the upper semisphere.
For C90-C270 symmetrical luminaires, indicated by Isym=3, the measured C-planes are listed starting at C0 (pos. 28). However, the luminous intensities are listed starting at the values of the C-270 plane via the C-0 plane in the order given in pos. 26. Example: C270, C285, C300, C315, C330, C345, C0, C15...