Hi Jarek,
The data is stored with the data URL (see link below). As you noted, that
URL has base64 prefixed by `data:image/png;base64,`, but isn't
`xs:base64Binary`. And this is why in the form definition, Form Builder puts
`<xf:bind type="xf:anyURI"/>`. This is correct, as a data URL is an
`xf:anyURI`.
Now you're saying that you would prefer the signature to be stored in
straight base64, so the form definition could have the type
`xs:base64Binary`? If so, is it maybe because you have a use case where it
is more convenient to have straight base64 than a data URL that contains
base64?
https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs