Listed only by Irwin, who says: A pedal mixture composed of either the incisive, small-scale Strings or the larger-scale pipes that sound more like Principals. This composite of tone supports the String ancillary or the Swell's Strings. Little approach to standardization of design is possible. The ranks usually do not break back in pitch as the scale is ascended, whereas manual ranks do. This permits the pedal scale to be ascended without changes in the weight or harmonic structure of the tone. Third-sounding ranks are less likely to be seen in pedal mixtures than they are in manual mixtures, since the pedal tone is more usable as a tone-builder than as a melody line. However, the 3-1/5' (or 1-3/5') can be included in this mixture if a more harmonically complete tone is desired. These pitches may all be taken from one rank of pipes (although this is not considered an orthodox procedure) if space or funds do not warrant individual, �straight� ranks. In this case special scaling of the pipes would have to be used by the builder to balance the loudness of the tone. Irwin understates the case against unifying a mixture: fifth and, especially, third sounding stops should never be unified from unison or octave sounding ranks, as they can never be brought into proper tune.