code: @Override
  	public void format(Buffer buf) {
  		int pos = 0;
  		// initial the number of records as 0
  		setVal(buf, pos, Constant.defaultInstance(INTEGER));
  		int flagSize = Page.maxSize(BIGINT);
  		pos += Page.maxSize(INTEGER);
  		// set flags
  		for (int i = 0; i < flags.length; i++) {
  			setVal(buf, pos, new BigIntConstant(flags[i]));
  			pos += flagSize;
  		}
  		int slotSize = BTreePage.slotSize(sch);
  		for (int p = pos; p + slotSize <= Buffer.BUFFER_SIZE; p += slotSize)
  			makeDefaultRecord(buf, p);
  	}
docs: Formats the page by initializing as many index-record slots as possible
  to have default values.
  
  @see PageFormatter#format(Buffer)