title: hexadecimal values in masm starting with a letter
body: <p>Do hexadecimal values in masm have to start with a number? If I use</p>
  
  <pre><code>.const
  
      _mmx_cons   QWORD f000000000000000h
  </code></pre>
  
  <p>I get a build error :</p>
  
  <pre><code>test.asm(26): error A2006: undefined symbol : f000000000000000h
  </code></pre>
  
  <p>But if I add a leading 0 </p>
  
  <pre><code>.const
  
      _mmx_cons   QWORD 0f000000000000000h
  </code></pre>
  
  <p>The error vanish. Why is that? Am I sure that it represents the 64 bit value <code>0xf000000000000000</code>?</p>