Clarify how 3DS units should be interpreted

Resolving #5

Author: petrvanekrobe

gdtf-spec.md

@@ -1066,7 +1066,7 @@ specified in [table 32](#user-content-table-32 ).
 | Width              | [Float](#user-content-attrtype-float )     | Unit: meter; Default value: 0 |
 | Height             | [Float](#user-content-attrtype-float )     | Unit: meter; Default value: 0 |
 | PrimitiveType      | [Enum](#user-content-attrtype-enum )       | Type of 3D model; The currently defined values are: “Undefined”, “Cube”, “Cylinder”, “Sphere”, “Base”, “Yoke”, “Head”, “Scanner”, “Conventional”, “Pigtail”, "Base1_1", "Scanner1_1", "Conventional1_1"; Default value: “Undefined” |
-| File               | [Resource](#user-content-attrtype-resource )   | Optional. File name without extension and without subfolder containing description of the model. Use the following as a resource file:<br />- 3DS or GLB to file to provide 3D model.<br />- SVG file to provide the 2D symbol.<br />It is possible to add several files with the same name but different formats. Preferable format for the 3D model is GLTF. The resource files are located in subfolders of a folder called <code>./models</code>. The names of the subfolders correspond to the file format of the resource files (3ds, step, svg). The path for 3ds files would be <code>./models/3ds</code>. For glb files, it would be <code>./models/gltf</code>.</p> Software that is utilizing GDTF files should always be able to read both 3ds and GlTF file formats and should be able to write at least one of these formats. It is preferable that only one type of 3D model file formats is used within one GDTF file. |
+| File               | [Resource](#user-content-attrtype-resource )   | Optional. File name without extension and without subfolder containing description of the model. Use the following as a resource file:<br />- 3DS or GLB to file to provide 3D model.<br />- SVG file to provide the 2D symbol.<br />It is possible to add several files with the same name but different formats. Preferable format for the 3D model is GLTF. The resource files are located in subfolders of a folder called <code>./models</code>. The names of the subfolders correspond to the file format of the resource files (3ds, step, svg). The path for 3ds files would be <code>./models/3ds</code>. For glb files, it would be <code>./models/gltf</code>.</p> Software that is utilizing GDTF files should always be able to read both 3ds and GlTF file formats and should be able to write at least one of these formats. It is preferable that only one type of 3D model file formats is used within one GDTF file.<br />All dimensions in 3DS files are interpreted in millimeters (1 unit = 1 mm).|
 | SVGOffsetX            | [Float](#user-content-attrtype-float )  | Offset in X from the 0,0 point to the desired insertion point of the top view svg. Unit based on the SVG. Default value: 0|
 | SVGOffsetY            | [Float](#user-content-attrtype-float )  | Offset in Y from the 0,0 point to the desired insertion point of the top view svg. Unit based on the SVG. Default value: 0|
 | SVGBottomOffsetX      | [Float](#user-content-attrtype-float )  | Offset in X from the 0,0 point to the desired insertion point of the bottom view svg. Unit based on the SVG. Default value: 0|