Not all elements in the SolidWorks drawing view can be automatically marked with a symbol. To mark such elements anyway, a free symbol of any type can be created.
Since a free symbol is not assigned to a SolidWorks feature, the user must enter all information manually and define the position of the symbol by clicking in the drawing view. A unique number is always guaranteed.
A description of the different feature types can be found in chapter Edit mark.
The content refers to version 2.0.0.0