LinPlug MorphoX - Manual (Page 48)

One of the powerful capabilities of the TUN file format and Scala, is the
ability to specify the pitch and midi note which will be the reference pitch for
the microtuning in use. This becomes a very important consideration when
one is using a number of different synthesizers and wishes to keep them in
tune with a given base frequency. It is very common for one to specify a
chosen concert pitch such as A440 Hz or C261.6256 Hz as a reference for
a microtuning, however, the flexibility of the TUN format and Scala enables
one to specify this frequency arbitrarily. In Scala this reference is called
Map Frequency.
As well as being able to specify the Map Frequency, one can also specify a
central midi-note, which will become the starting point for the microtuning in
use. Being able to specify a particular midi-note on the controller, provides
a way to map a microtuning beginning on any desired midi key, making it
easier to navigate the keyboard when there may be more or less than 12
tones per octave, or where one may desire to have the notes of a tuning fall
on certain physical keys.
Important Note
When one uses a TUN microtuning-file in the MorphoX, the above specified
mapping properties will override the Master Tuning reference. Normally
when one is using the default 12 Tone Equal Tempered Scale, the Master
Tuning will be used to make fine pitch adjustments around the standard
concert pitch of A440 Hz, but when one has specified another pitch base for
a microtuning when the TUN file is created in Scala, such as C261.6256
Hz, the data in the TUN microtuning-file will provide a new pitch reference.
MorphoX user manual 1.1.0 page 48