Interpreting Ternary Phase Diagram Stoichiometry

I am trying to locate the lowest-melting mixture in a system of three nitrate salts: sodium, potassium, and calcium nitrate. I have the relevant ternary phase diagram, but I am unsure exactly about interpreting it because of the "doubled" stoichiometry of the sodium and potassium salts on the plot.


[![Ternary phase diagram](https://i.stack.imgur.com/4Qw68.png)](https://i.stack.imgur.com/4Qw68.png)


I posit that along the drawn-in red line, there is a 50/50 molar mixture of Ca(NO3)2 and (KNO3)2. At the zero NaNO3 limit, this would give 0.5 mol Ca(NO3)2 and 1 mol KNO3, so I understand the composition to be 33.3 mole percent Ca(NO3)2 and 66.7 mole percent KNO3. Is my interpretation correct?


