The RFC3986 path may be empty – which is essentially the same as absent. Also, when magnet-URI was composed, the URI spec was RFC 2396, which clearly describes

The RFC3986 path may be empty – which is essentially the same as absent. Also, when magnet-URI was composed, the URI spec was RFC 2396, which clearly describes <path> is one of the elements that "may be absent": https://tools.ietf.org/html/rfc2396#section-3 https://tools.ietf.org/html/rfc2396#section-3 Also both RFC2396 and RFC3986 allow for URI schemes where everything after the 'scheme:' is opaque, and need not be strictly interpretable as authority/path/etc. (RFC2396 mentions that it will still refer to this opaque-part as a 'path', because "they are mutually exclusive for any given URI and can be parsed as a single component".)