When attributes are created on cells, they become parameters to that cell. Each instance of the cell has a copy of the attribute placed on the node, and the node's attribute can then be set independently of the cell's attribute. In such a situation, the node attribute's value is the "actual" parameter to the cell, and the cell attribute's value if the "formal", or default parameter value.

One example of the use of cell parameters is in the SPICE primitives where user-defined values (such as voltage) are communicated into the icon for generation in the SPICE deck (see Section 8-4-4).

Another use of cell parameters is to parameterize the size of a transistor in a schematic (or to parameterize the scalable layout transistors in the MOSIS CMOS technology, see Section 7-4-2) The transistor width and length can be defined in terms of the parameter value, allowing a single cell to take on many different forms. By combining these parameters with the interpretive language facility, an arbitrary mathematical expression can be placed on the transistor which combines parameter values to form the exact transistor size .

Inside of the cell, the parameter is shown with its name, default value, and actual value from up the hierarchy. When first defined, the parameter has no actual value, and so appears as "Strength=?;def=2" (for an attribute called "Strength" with a value of 2). If an instance is created and its "Strength" attribute is set to 7, then descending into that cell will show "Strength=7;def=2".

In schematics, the location of a parameter on an icon is determined by the location of that parameter on the sample icon, inside of the schematic cell.

If a parameter is changed on a cell, you may wish the change to affect all instances of that cell. To do this, use the Update Attributes Inheritance on Node command (in menu Edit / Properties). To do this everywhere, use the Update Attributes Inheritance all Libraries command.

If you do not wish to see a parameter's text on any instance, select the parameter text inside of the cell, use the Object Properties... command (in menu Edit / Properties), and check "Invisible outside cell".

You can disable the display of parameters on cell instances by selecting them and using the Hide All Attributes on Node command (in menu Edit / Properties). You can force all parameters to be displayed on a cell instance by using the Hide All Attributes on Node command. To restore default parameter visibility on a cell instance, use the Default Attribute Visibility command.