# File lib/spreadsheet/excel/writer/worksheet.rb, line 639
  def write_mulrk row, idx, multiples
    fmt = 'v2'
    data = [
      row.idx, # Index to row
      idx, # Index to first column (fc)
    ]
    # List of nc=lc-fc+1 16-bit indexes to XF records (➜ 6.115)
    multiples.each_with_index do |cell, cell_idx|
      xf_idx = @workbook.xf_index @worksheet.workbook, row.format(idx + cell_idx)
      data.push xf_idx, encode_rk(cell)
      fmt << 'vV'
    end
    # Index to last column (lc)
    data.push idx + multiples.size - 1
    write_op opcode(:mulrk), data.pack(fmt << 'v')
  end