data:[media-type][;base64],data
Data URLs contain MIME data in the URL itself. They are defined in RFC 2397.
media-type is a MIME ‘Content-Type’ string, possibly including parameters. It defaults to ‘text/plain;charset=US-ASCII’. The ‘text/plain’ can be omitted but the charset parameter supplied. If ‘;base64’ is present, the data are base64-encoded.