def write_url(row, col, url, string=url, format=nil)
record = 0x01B8
length = 0x0034 + 2 * (1+url.length)
write_string(row,col,string,format)
header = [record, length].pack("vv")
data = [row, row, col, col].pack("vvvv")
unknown = "D0C9EA79F9BACE118C8200AA004BA90B02000000"
unknown += "03000000E0C9EA79F9BACE118C8200AA004BA90B"
stream = [unknown].pack("H*")
url = url.split('').join("\0")
url += "\0\0\0"
len = url.length
url_len = [len].pack("V")
append(header + data)
append(stream)
append(url_len)
append(url)
end