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<h5 class="subsubsection">9.28.3.3 Register names</h5>

<p><a name="index-register-names_002c-MMIX-1683"></a><a name="index-MMIX-register-names-1684"></a>
Local and global registers are specified as &lsquo;<samp><span class="samp">$0</span></samp>&rsquo; to &lsquo;<samp><span class="samp">$255</span></samp>&rsquo;. 
The recognized special register names are &lsquo;<samp><span class="samp">rJ</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rA</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rB</span></samp>&rsquo;,
&lsquo;<samp><span class="samp">rC</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rD</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rE</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rF</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rG</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rH</span></samp>&rsquo;,
&lsquo;<samp><span class="samp">rI</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rK</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rL</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rM</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rN</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rO</span></samp>&rsquo;,
&lsquo;<samp><span class="samp">rP</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rQ</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rR</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rS</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rT</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rU</span></samp>&rsquo;,
&lsquo;<samp><span class="samp">rV</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rW</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rX</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rY</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rZ</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rBB</span></samp>&rsquo;,
&lsquo;<samp><span class="samp">rTT</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rWW</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rXX</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rYY</span></samp>&rsquo; and &lsquo;<samp><span class="samp">rZZ</span></samp>&rsquo;.  A leading
&lsquo;<samp><span class="samp">:</span></samp>&rsquo; is optional for special register names.

   <p>Local and global symbols can be equated to register names and used in
place of ordinary registers.

   <p>Similarly for special registers, local and global symbols can be used. 
Also, symbols equated from numbers and constant expressions are allowed in
place of a special register, except when either of the options
<code>--no-predefined-syms</code> and <code>--fixed-special-register-names</code> are
specified.  Then only the special register names above are allowed for the
instructions having a special register operand; <code>GET</code> and <code>PUT</code>.

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