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<div class="subtitle">Description</div>

<p>
This function extracts the quantum numbers of the spins constituting
the spin system described by the structure <code>System</code>. It is a row
vector of spin quantum numbers.
</p>

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<div class="subtitle">Examples</div>

<p>
If we define a spin system <code>ABC</code> with
</p>

<pre class="matlab">
ABC = struct('S',1/2,'g',[2 2 2.3],'Nucs','63Cu,14N','A',[10 10 2