From Xojo Documentation
A null-terminated String. You can pass a regular REALbasic String to it and it will be terminated with a null byte automatically. Also, CString does an implicit type conversion to String when you assign a CString to a String variable.
Declare statement; Boolean, Byte, CFStringRef, Color, Currency, Delegate, Double, Int8, Int16, Int32, Int64, Integer, OSType, PString, Ptr, Short, Single, String, UByte, UInt8, UInt16, UInt32, UInt64, UShort, Variant, WindowPtr, WString data types.