The CLASS command is used to define or use net classes.
Without parameters, it offers a dialog in which the net classes can be defined.
If only a number or name is given, the net class with the given number or name is selected and will be used for subsequent NET and SIGNAL commands.
If both a number and a name are given, the net class with the given number will be assigned all the following values and will also be used for subsequent NET and SIGNAL commands. If any of the parameters following name are omitted, the net class will keep its respective value.
If number is negative, the net class with the absolute value of number will be cleared. The default net class 0 can't be cleared.
Net class names are handled case insensitive, so SUPPLY would be the same as Supply or SuPpLy.
Using several net classes in a drawing increases the time the Design Rule Check and Autorouter need to do their job. Therefore it makes sense to use only as few net classes as necessary (only the number of net classes actually used by nets or signals count here, not the number of defined net classes).
In order to avoid conflicts when CUT/PASTEing between drawings it makes sense to define the same net classes under the same numbers in all drawings.
The Autorouter processes signals sorted by their total width requirements (Width plus Clearance), starting with those that require the most space. The bus router only routes signals with net class 0.
The net class of an existing net/signal can be changed with the CHANGE command. Any changes made by the CLASS command will not be stored in the UNDO/REDO buffer.
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