@lanodan @domi @easrng prospero:// URLs from 1738 use ;parameters
also RFC2396 requires escaping it in path segments b/c its used for path params:
path = [ abs_path | opaque_part ] path_segments = segment *( "/" segment ) segment = *pchar *( ";" param ) param = *pchar pchar = unreserved | escaped | ":" | "@" | "&" | "=" | "+" | "$" | ","An example of a URI scheme using params is IMAP: imap://joe@example.com/INBOX/;uid=20/;section=1.2