Adding tdc as overlays

With File --> Add Overlay → Vector it is also possible to add tdc files. Because tdc files have no embedded CRS information it is possible to put a projection file aside with extension *.tdc.prj.
If this prj is existent e.g. after building generation or manual assignment the tdc can be overlayed without further CRS definition needed.
The tdc and shape overlays can be used as snap target during geometry editing. To enable a tdc or shape overlay as snap target the appropriate checkbox in the Layer window must be checked.

With a right mouse click on the overlay name it is possible to edit the style (color, line width).