Composing Music by William Russo: Chapter 6
Isomelody and Isorhythm
An isomelody is a series of pitches that differs from a standard row and a 12-tone row in the following ways; each tone may be used only as originally given (123456; not 1112234566), and octave forms of the tones are not allowed.
An isorhythm is a rhythm that is repeated consecutively.
If an isomelody and an isorhythm are in sync, this is called an ostinato (more on that in Chapter 7). If they are out of sync, they will create patterns that diverge and converge.
Here is my isomelody and isorhythm combined (plus accompaniment):