LinPlug Octopus - Manual (Page 54)

Scala may be used to create the TUN format microtuning files needed to
explore microtunings with this software instrument.
The Scala home page is http://www.xs4all.nl/~huygensf/scala/
Specifying the Reference Frequency of a Microtuning
One of the powerful capabilities of the TUN file format and Scala, is the
ability to specify the frequency and MIDI-Note which will become the
reference pitch, or starting note for a microtuning. This becomes a very
important consideration when one is using a number of different
synthesizers and wishes to keep them in all tune with a given base
frequency. It is very common for a musician to need to specify a certain
concert pitch such as A440 Hz (MIDI-Note 69) or C261.6256 Hz (MIDI-Note
60) as a reference for a microtuning, however, the flexibility of the TUN
format and Scala enables one to specify this frequency arbitrarily, so that
any chosen starting frequency may be assigned to any desired MIDI-Note.
In Scala this reference is called the Map Frequency.
Being able to specify a particular MIDI-Note reference and its associated
Map Frequency on the MIDI controller, provides a way to map a microtuning
to begin on any desired MIDI key, making it easier to navigate the
instrument when there may be more or less than 12 tones per octave, or
where one may have a musical need to map the notes of a microtuning to
fall on certain physical keys.
52 Manual