Public MustOverride Function reserveVolume ( _
	user As String, _
	volume As Long, _
	billingText As String, _
	username As String, _
	password As String _
) As Charging

public abstract Charging reserveVolume (
	string user,
	long volume,
	string billingText,
	string username,
	string password
)

public:
virtual Charging^ reserveVolume (
	String^ user, 
	long long volume, 
	String^ billingText, 
	String^ username, 
	String^ password
) abstract