title: What does this line of FormulaR1C1 mean?
body: <p>I get what FormulaR1C1 means from this <a href="https://stackoverflow.com/questions/29739494/what-does-r-115c-mean-in-vba-for-excel-2011-on-mac">link</a>.<br>
  But I couldn't get it when it was used with an ampersand <code>&amp;</code> in VBA and <em>Vlookup</em> here in this line:</p>
  
  <pre><code>.Range(Cells(2, 3), Cells(2, 79)).FormulaR1C1 = "=VLOOKUP(RC1&amp;R1C,POR_Vert!C4:C6,3,FALSE)"
  </code></pre>