Editing MathML Notations
Oxygen XML Author Eclipse plugin includes a built-in editor for MathML notations. To start the MathML editor, double-click a MathML notation (for embedded notations, you can also select the Edit Equation action from its contextual menu).
Tip:
For editing MathML equations, you can also try free choices, such as
Apache OpenOffice Math or LibreOffice Math.