generic_stream::is_derived

Source: stream/generic/generic_stream__is_derived.pro

 generic_stream::is_derived
        Return whether the stream is a "derived" stream.
 
 Usage:
        state = strref -> is_derived()

 Notes:
        Derived streams are things like spectral-index time series
        which do not have raw data, and consequently lock the dataset.

 History:
        Original: 13/7/00; SJT
        Drop flag and use specifics: 3/5/02; SJT