# Export for Layer-based Software

Some software products may require a layer structure to be added to the IFC classification. Revit automatically assigns the layer value according to the default CAD (.dwg/.dgn) mapping file. The default configuration file is: C:\ProgramData\Autodesk\ RVT 20xx\exportlayers-dwg-AIA.txt

The configuration found in this file can be adapted from the Revit UI when selecting Export > Options > Export settings DWG/DXF or manually using the syntax:

\<Revit Category Name>\<tab>\<tab>\<Layer Name>

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The reference to a custom layer reference file needs to be added to the Revit.ini file which can be found in the following location: C:\Users\\\<USER>\AppData\Roaming\ Autodesk\Revit\Autodesk Revit 20xx

The full path to the layer reference file is added in the line starting with ExportLayersNameDGN=

For Example: ExportLayersNameDGN=C:\Users\\\<USER>\Documents\RevitLayers.txt Just like with the class mapping, sometimes it is needed to assign the layer value on the element level. For this, you can use the shared parameter *IfcPresentationLayer,* which is of course included in the official shared parameter files.