CommPort limited to 16?

When using the MSComm Control, is it possible to use a CommPort number higher than 16?

In Microsoft's document they say,
'You can set this value to any number from 1 through 16 at design time. ' But when I try to open a higher number in run-time, it says error 'port already open'. But, I can open the higher port by using hyperterminal.

Is it a VB's limit?

Thanks