### The Clearance Matrix

In the window with the Clearance Matrix you can define the spacing rules between the object types. This is done via clearance classes. An Item clearance class is described by the definition of a minimal spacing to items of all existing clearance classes. These values can be looked up and changed in the Clearance Matrix

Predefined are the clearance classes null and default. Items of the clearance class null have a minimal spacing of 0 to all other items. This value cannot be changed in the Clearance Matrix.

In the Specctra-DSN-Format there exist only the hard coded clearance classes pin, smd, via, wire, area and testpoint. When reading the DSN-file at the program start the clearance classes of the host system will be taken over. The class wire will be renamed to default. The rest of the hard coded clearance classes will only be generated, if values for these classes are found in the DSN-file.

#### To add a new clearance class

Press the button Add Class and enter the name of the new class into the dialog field, which is popping up. The Clearance Matrix will be extended by a row and a column with the values for the new class. Change the predefined values in the new row according to your needs.

#### To remove redundant clearance classes

By pushing the Trim Button you can remove classes as redundant, whose entries in the Clearance Matrix are exact equal to the entries of an other class. All items belonging to the deleted clearance class will then be assigned to this other clearance class.

#### Layer dependent clearance classes

In the layer field on top of the window you see the layers, for which the entries in the Clearance Matrix are valid. When all is selected in the combo box, the matrix entries are valid on all layers. If in this case layer dependent clearance values are defined for a special field, the value -1 is displayed, because it is not possible to output a value, which is valid on all layers. Analog if inner is selected in the combo box. You can view or edit a layer dependent clearance value after selecting the name of the layer of your choice in the layer combo box.