ICANotes users have the option of specifying a service code have zero units.
Presently in ICANotes, when no value is added to the units field, the system will assume a total of 1 unit. More than one unit may be entered. However, if zero units are specified, the accompanying service charge will revert to $0.00 and the note will produce an error message when prepping for billing submission in the Billing/Productivity Report:
Please watch Tyler's video demonstrating how the zero unit values works in ICANotes: