To Define Net Pairs
1. Click Analysis > Electrical Clearance. The Clearance and Creepage dialog box opens.
2. Click Setup > Net Pairs. The Net Pairs dialog box opens and displays a table with names of all the nets in the first row and first column.  
3. Select a Pairing method to define the net pairs. The following pairing methods are available:
Select cells to pair nets—Click a check box in any cell. The net in the row is paired with the net in the column. This is the default pairing method.
Select nets to pair them among themselves—Select more than one row. The selected nets are paired among themselves.
Select nets to pair them with unselected nets—Select one or more rows. The selected nets are paired with the nets that are not selected.
Pair all nets—Do not select any nets in the table. All nets are paired among themselves by default.
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You cannot pair a net with itself or an empty net with any other net.
4. After you have defined the net pairs for the analysis, click OK.