\multicolumn {cols} {pos} {text}

  The \multicolumn is used to make an entry that spans several columns.
  The first mandatory argument, cols, specifies the number of columns
  to span.  The second mandatory argument, pos, specifies the
  formatting of the entry; c for centered, l for flushleft, r for
  flushright.  The third mandatory argument, text, specifies what text
  is to make up the entry.