code: private String readName(ByteBuffer buf) throws IOException
      {
          ISMatTag tag = new ISMatTag(buf);
  
          return tag.readToString();
      }
docs: Reads Matrix name.
  
  Modifies <code>buf</code> position.
  
  @param buf <code>ByteBuffer</code>
  @return name <code>String</code>
  @throws IOException if reading from buffer fails