These units generate and process non-standard signal data types, such as down-sampled time-domain control signals and audio signals, and their frequency-domain (spectral) representations. The data types (d-, w-) are self-defining, and the contents are not processable by any other Csound units.

The opcodes for non-standard spectral processing are specaddm, specdiff, specdisp, specfilt, spechist, specptrk, specscal, specsum, and spectrum.