f$isnullstring (f$IstNullText)

This function verifies if the given parameter has a value. If the parameter is NOVAL or UNDEF, " or the specified default value is returned. If the parameter has a value, it is returned. The parameter must be of string type.

Syntax:	Value = f$isnullstring(Parametername[,Default])
	Argument	Type	Meaning
	ParaName	String	Name of the parameter to be verified
	Default (Optional)	String	Return value if the parameter is NOVAL or UNDEF.
Result:	String	Parameter value, default value, or "
Example:	Date = f$isnullstring('Date') Date is '' if it is not occupied or Date = f$isnullstring('Date',f$Date()) Date contains the day's date if it is unoccupied.