Sagittal is a microtonal notation system capable of notating almost any conceivable tuning. It was developed by Dave Keenan and George Secor with significant contributions from numerous others.

Resources

Official site

Sagittal Forum

The original Xenharmonikon article

Gift of the Gods: a Mythical introduction to Sagittal notation

spreadsheet-based calculator for Sagittal JI notation

Sagittal-SMuFL-Map, a table of every Sagittal symbol

Pain free guide to Sagittal by William Lynch

Sagittal notation guide for 24edo by William Lynch

Introductory examples by Hans Straub

Sagittal chord chart by Andrew Meronek

Notation Software Support

Sibelius

Sagibelius 2.0 - plugins for using Sagittal notation in Sibelius 4 and up. By Jacob Barton. Hosted on this wiki. Donationware.

Sagibelius_2.0.zip

Lilypond

Plugin for Sagitall notation in Lilypond by Graham Breed

MuseScore

Sagittal accidentals are available in MuseScore via the Bravura font which implements the SMuFL standard. They can be accessed by opening the Master Palette and finding them in the Symbols section at the end.

Scala

Sagittal notation is available in Scala.

Dorico

Because Dorico is built by Steinberg Media, the same company that maintains the SMuFL standard, it should support Sagittal.

Scores in Sagittal notation