*SetDefaultSystemInstance()
Specifies the varname and label that should be used when instantiating the system.
Syntax
*SetDefaultSystemInstance(varname, "definitionlabel")
    Arguments
- varname
 - The varname to when this system definition gets loaded via the System panel.
 - "definition label"
 - The label the user interface will recommend when adding or replacing an assembly or analysis.
 
Example
*SetDefaultSystemInstance(sys_frnt_susp)
*SetDefaultSystemInstance( , Front Suspension)
    Comments
Varname is currently only used in 10.0 or older models. It is ignored with the new assembly concepts.
- Data Label
 - Definition Label
 - Auto-generated Label (Assembly 0)