max number of desgeo members

Hello i just got to know the command desgeo can help to figure out whether a spco is used in the design module.

i use unset(desgeo) to convert the answer to logical word .so it can just give me a simple response( true or  false ).

anyone know how to convert the answer of desgeo into a number ? i just need number of a spco element used in the design module.

Thanks in advance