Slendro
Slendro is a tuning system used in both Javanese and Balinese gamelan music. It provides an octave-repeating pentatonic scale, although the octave is usually stretched to compensate for the inharmonicity of the instruments.
In Javanese gamelan, the tones of slendro are numbered 1 2 3 5 6. Tuning varies between gamelan, but most modern Javanese sets encountered in the US seem to be a familiar major pentatonic scale with 3 as the "tonic," but with considerable equalization in the direction of 5edo. However, it's important to note that slendro is not 5edo.
Traditionally, there are three pathet or modes of slendro. Slendro manyuro emphasizes 2 and 6 with an "enemy tone" of 5, and slendro songo 5 and 1 with an enemy tone of 3. Enemy tones are pitches that elaborating instruments generally avoid emphasizing. Finally, slendro nem is a "miscellany" term that may contain any mixture of slendro manyuro and slendro songo. Most slendro nem pieces are not traditional court gamelan works.
See also
Todo: expand