In 1825, Felix Mendelssohen Bartholdy composed his String Octet. This work is classed in 785.7198 String ensembles for eight players. In the same program I mentioned in last Friday’s blog, the National Symphony Orchestra played an arrangement of the octet for string orchestra. Does one class this arrangement in 785.7198 with the original score, or in a different number? Again, the instructions in 780 Music indicate that a work is classed with the executant—the voice or instrument that produces the music. Thus, the arrangement must be classed at 784.7 String orchestra. But, arranged music for string orchestra can be shown by adding notation 1 from the add table at 784.3-785.9 Other orchestral combinations and band and then notation 38 from 781.38 Arrangements. The original voice, instrument, ensemble of the arrangement is shown by adding to notation 38 the numbers following 78 in 782-788, e.g., notation 57198 from 785.7198 String ensembles for eight players. Thus, the DDC number for this arrangement is 784.713857198 Arrangements for string orchestra of music for string ensembles for eight players.