Fix broken links in the documentation.

22 files changed, 49 insertions, 51 deletions

diff --git a/guide/src/chapter_03.md b/guide/src/chapter_03.md
index d7f8b4b9..1ced76cb 100644
--- a/guide/src/chapter_03.md
+++ b/guide/src/chapter_03.md
@@ -6,7 +6,7 @@ will cover some of them, starting from a high level parser, the
 down to the actual OpenPGP [`PacketParser`].
 
 [`CertParser`]: ../../sequoia_openpgp/cert/struct.CertParser.html
-[`Cert`]: ../../sequoia_openpgp/struct.Cert.html
+[`Cert`]: ../../sequoia_openpgp/cert/struct.Cert.html
 [`PacketParser`]: ../../sequoia_openpgp/parse/struct.PacketParser.html
 
 # Parsing Certs
@@ -101,7 +101,7 @@ turned into a vector of [`Packet`]s:
 
 [`PacketPile`]: ../../sequoia_openpgp/struct.PacketPile.html
 [`Packet`]: ../../sequoia_openpgp/enum.Packet.html
-[`Cert::from_packet_pile`]: ../../sequoia_openpgp/struct.Cert.html#method.from_packet_pile
+[`Cert::from_packet_pile`]: ../../sequoia_openpgp/cert/struct.Cert.html#method.from_packet_pile
 [`Message::from_packet_pile`]: ../../sequoia_openpgp/struct.Message.html#method.from_packet_pile
 
 ```rust
diff --git a/ipc/src/assuan/mod.rs b/ipc/src/assuan/mod.rs
index 3ad88d88..75e05f6e 100644
--- a/ipc/src/assuan/mod.rs
+++ b/ipc/src/assuan/mod.rs
@@ -92,9 +92,9 @@ impl Client {
     /// [`Connection::data()`], or the operation may be canceled using
     /// [`Connection::cancel()`].
     ///
-    /// [`Response::Ok`]: enum.Response.html#variant.Ok
-    /// [`Response::Error`]: enum.Response.html#variant.Error
-    /// [`Response::Inquire`]: enum.Response.html#variant.Inquire
+    /// [`Response::Ok`]: ../assuan/enum.Response.html#variant.Ok
+    /// [`Response::Error`]: ../assuan/enum.Response.html#variant.Error
+    /// [`Response::Inquire`]: ../assuan/enum.Response.html#variant.Inquire
     /// [`Connection::data()`]: #method.data
     /// [`Connection::cancel()`]: #method.cancel
     ///
@@ -147,9 +147,9 @@ impl Client {
     /// and `Error` indicate success and failure of the original
     /// operation that lead to the current inquiry.
     ///
-    /// [`Response::Ok`]: enum.Response.html#variant.Ok
-    /// [`Response::Error`]: enum.Response.html#variant.Error
-    /// [`Response::Inquire`]: enum.Response.html#variant.Inquire
+    /// [`Response::Ok`]: ../assuan/enum.Response.html#variant.Ok
+    /// [`Response::Error`]: ../assuan/enum.Response.html#variant.Error
+    /// [`Response::Inquire`]: ../assuan/enum.Response.html#variant.Inquire
     pub fn data<'a, C: 'a>(&'a mut self, data: C) -> Result<()>
         where C: AsRef<[u8]>
     {
diff --git a/net/src/wkd.rs b/net/src/wkd.rs
index a4134110..663e0d57 100644
--- a/net/src/wkd.rs
+++ b/net/src/wkd.rs
@@ -8,7 +8,7 @@
 //! See the [get example].
 //!
 //! [draft-koch]: https://datatracker.ietf.org/doc/html/draft-koch-openpgp-webkey-service/#section-3.1
-//! [get example]: get#example
+//! [get example]: fn.get.html#example
 //!
 
 
@@ -252,8 +252,6 @@ fn parse_body<S: AsRef<str>>(body: &[u8], email_address: S)
 /// Retrieves the Certs that contain userids with a given email address
 /// from a Web Key Directory URL.
 ///
-/// This function is call by [net::wkd::get](../../wkd/fn.get.html).
-///
 /// From [draft-koch]:
 ///
 /// ```text
diff --git a/openpgp-ffi/src/armor.rs b/openpgp-ffi/src/armor.rs
index 4ce8187d..f0da2905 100644
--- a/openpgp-ffi/src/armor.rs
+++ b/openpgp-ffi/src/armor.rs
@@ -2,7 +2,7 @@
 //!
 //! Wraps [`sequoia-openpgp::armor`].
 //!
-//! [`sequoia-openpgp::armor`]: ../../sequoia_openpgp/armor/index.html
+//! [`sequoia-openpgp::armor`]: ../../../sequoia_openpgp/armor/index.html
 
 use std::mem::size_of;
 use std::ptr;
diff --git a/openpgp-ffi/src/cert.rs b/openpgp-ffi/src/cert.rs
index 90aac1ea..2d18ff18 100644
--- a/openpgp-ffi/src/cert.rs
+++ b/openpgp-ffi/src/cert.rs
@@ -2,8 +2,8 @@
 //!
 //! Wraps [`sequoia-openpgp::Cert`] and [related functionality].
 //!
-//! [`sequoia-openpgp::Cert`]: ../../sequoia_openpgp/struct.Cert.html
-//! [related functionality]: ../../sequoia_openpgp/cert/index.html
+//! [`sequoia-openpgp::Cert`]: ../../../sequoia_openpgp/cert/struct.Cert.html
+//! [related functionality]: ../../../sequoia_openpgp/cert/index.html
 
 use std::ptr;
 use std::slice;
@@ -140,7 +140,7 @@ fn pgp_cert_fingerprint(cert: *const Cert)
 ///
 /// This object writes out secret keys during serialization.
 ///
-/// [`TSK`]: cert/struct.TSK.html
+/// [`TSK`]: ../tsk/struct.TSK.html
 #[::sequoia_ffi_macros::extern_fn] #[no_mangle] pub extern "C"
 fn pgp_cert_as_tsk(cert: *const Cert) -> *mut TSK<'static> {
     cert.ref_raw().as_tsk().move_into_raw()
diff --git a/openpgp-ffi/src/crypto.rs b/openpgp-ffi/src/crypto.rs
index d4e7ace9..4bc35f5b 100644
--- a/openpgp-ffi/src/crypto.rs
+++ b/openpgp-ffi/src/crypto.rs
@@ -2,7 +2,7 @@
 //!
 //! Wraps [`sequoia-openpgp::crypto`].
 //!
-//! [`sequoia-openpgp::crypto`]: ../../sequoia_openpgp/crypto/index.html
+//! [`sequoia-openpgp::crypto`]: ../../../sequoia_openpgp/crypto/index.html
 
 use libc::size_t;
 
diff --git a/openpgp-ffi/src/fingerprint.rs b/openpgp-ffi/src/fingerprint.rs
index a74f64f0..549311b5 100644
--- a/openpgp-ffi/src/fingerprint.rs
+++ b/openpgp-ffi/src/fingerprint.rs
@@ -8,7 +8,7 @@
 //!
 //! Wraps [`sequoia-openpgp::Fingerprint`].
 //!
-//! [`sequoia-openpgp::Fingerprint`]: ../../sequoia_openpgp/enum.Fingerprint.html
+//! [`sequoia-openpgp::Fingerprint`]: ../../../sequoia_openpgp/enum.Fingerprint.html
 
 use std::slice;
 use libc::{c_char, size_t};
@@ -29,7 +29,7 @@ use crate::RefRaw;
 ///
 /// Wraps [`sequoia-openpgp::Fingerprint`].
 ///
-/// [`sequoia-openpgp::Fingerprint`]: ../../sequoia_openpgp/enum.Fingerprint.html
+/// [`sequoia-openpgp::Fingerprint`]: ../../../sequoia_openpgp/enum.Fingerprint.html
 #[crate::ffi_wrapper_type(prefix = "pgp_",
                      derive = "Clone, Debug, Display, Hash, PartialEq")]
 pub struct Fingerprint(openpgp::Fingerprint);
diff --git a/openpgp-ffi/src/keyid.rs b/openpgp-ffi/src/keyid.rs
index 8c1bd21e..8ec550a0 100644
--- a/openpgp-ffi/src/keyid.rs
+++ b/openpgp-ffi/src/keyid.rs
@@ -8,7 +8,7 @@
 //!
 //! Wraps [`sequoia-openpgp::KeyID`].
 //!
-//! [`sequoia-openpgp::KeyID`]: ../../sequoia_openpgp/enum.KeyID.html
+//! [`sequoia-openpgp::KeyID`]: ../../../sequoia_openpgp/enum.KeyID.html
 
 use std::slice;
 use libc::{c_char};
@@ -29,7 +29,7 @@ use crate::MoveIntoRaw;
 ///
 /// Wraps [`sequoia-openpgp::KeyID`].
 ///
-/// [`sequoia-openpgp::KeyID`]: ../../sequoia_openpgp/enum.KeyID.html
+/// [`sequoia-openpgp::KeyID`]: ../../../sequoia_openpgp/enum.KeyID.html
 #[crate::ffi_wrapper_type(prefix = "pgp_", name = "keyid",
                      derive = "Clone, Debug, Display, Hash, PartialEq")]
 pub struct KeyID(openpgp::KeyID);
diff --git a/openpgp-ffi/src/lib.rs b/openpgp-ffi/src/lib.rs
index 1ec4ad50..a3991f50 100644
--- a/openpgp-ffi/src/lib.rs
+++ b/openpgp-ffi/src/lib.rs
@@ -134,7 +134,7 @@
 //! or the allocation for the string failed, which is considered
 //! undefined behavior.
 //!
-//! [`pgp_fingerprint_to_string`]: struct.Fingerprint.html#method.pgp_fingerprint_to_string
+//! [`pgp_fingerprint_to_string`]: fingerprint/struct.Fingerprint.html#method.pgp_fingerprint_to_string
 //!
 //! Failing functions signal failure either in-band (e.g. `NULL`, or
 //! -1), using `pgp_status_t`, and may store complex error information
@@ -145,7 +145,7 @@
 //! on the other hand, will return `NULL` and store a complex error at
 //! the location given using the `errp` parameter.
 //!
-//! [`pgp_fingerprint_from_hex`]: struct.Fingerprint.html#method.pgp_fingerprint_from_hex
+//! [`pgp_fingerprint_from_hex`]: fingerprint/struct.Fingerprint.html#method.pgp_fingerprint_from_hex
 //! [`pgp_packet_parser_from_bytes`]: parse/fn.pgp_packet_parser_from_bytes.html
 //!
 //! Errors may be inspected using [`pgp_error_status`], and formatted
diff --git a/openpgp-ffi/src/packet/key.rs b/openpgp-ffi/src/packet/key.rs
index 73d8350d..e774fd43 100644
--- a/openpgp-ffi/src/packet/key.rs
+++ b/openpgp-ffi/src/packet/key.rs
@@ -25,9 +25,9 @@ type UnspecifiedKey =
 ///
 ///   [Section 5.5 of RFC 4880]: https://tools.ietf.org/html/rfc4880#section-5.5
 ///
-/// Wraps [`sequoia-openpgp::packet::key::Key`].
+/// Wraps [`sequoia-openpgp::packet::Key`].
 ///
-/// [`sequoia-openpgp::packet::key::Key`]: ../../sequoia_openpgp/packet/key/struct.Key.html
+/// [`sequoia-openpgp::packet::key::Key`]: ../../../../sequoia_openpgp/packet/enum.Key.html
 #[crate::ffi_wrapper_type(prefix = "pgp_",
                      derive = "Clone, Debug, PartialEq, Parse")]
 pub struct Key(UnspecifiedKey);
diff --git a/openpgp-ffi/src/packet/literal.rs b/openpgp-ffi/src/packet/literal.rs
index 61d32f41..cf84e038 100644
--- a/openpgp-ffi/src/packet/literal.rs
+++ b/openpgp-ffi/src/packet/literal.rs
@@ -28,7 +28,7 @@ use crate::RefRaw;
 ///
 /// Wraps [`sequoia-openpgp::packet::literal::Literal`].
 ///
-/// [`sequoia-openpgp::packet::literal::Literal`]: ../../sequoia_openpgp/packet/literal/struct.Literal.html
+/// [`sequoia-openpgp::packet::literal::Literal`]: ../../../../sequoia_openpgp/packet/literal/struct.Literal.html
 #[crate::ffi_wrapper_type(prefix = "pgp_",
                      derive = "Debug, Parse, Serialize")]
 pub struct Literal(openpgp::packet::Literal);
diff --git a/openpgp-ffi/src/packet/mod.rs b/openpgp-ffi/src/packet/mod.rs
index deef792a..d3392c99 100644
--- a/openpgp-ffi/src/packet/mod.rs
+++ b/openpgp-ffi/src/packet/mod.rs
@@ -43,7 +43,7 @@ use crate::RefRaw;
 ///
 /// Wraps [`sequoia-openpgp::Packet`].
 ///
-/// [`sequoia-openpgp::Packet`]: ../../sequoia_openpgp/enum.Packet.html
+/// [`sequoia-openpgp::Packet`]: ../../../sequoia_openpgp/enum.Packet.html
 #[crate::ffi_wrapper_type(prefix = "pgp_",
                      derive = "Clone, Debug, Hash, PartialEq")]
 pub struct Packet(openpgp::Packet);
diff --git a/openpgp-ffi/src/packet/signature.rs b/openpgp-ffi/src/packet/signature.rs
index 64a81281..9b41282a 100644
--- a/openpgp-ffi/src/packet/signature.rs
+++ b/openpgp-ffi/src/packet/signature.rs
@@ -31,9 +31,9 @@ use crate::RefRaw;
 ///
 ///   [Section 5.2 of RFC 4880]: https://tools.ietf.org/html/rfc4880#section-5.2
 ///
-/// Wraps [`sequoia-openpgp::packet::signature::Signature`].
+/// Wraps [`sequoia-openpgp::packet::Signature`].
 ///
-/// [`sequoia-openpgp::packet::signature::Signature`]: ../../sequoia_openpgp/packet/signature/struct.Signature.html
+/// [`sequoia-openpgp::packet::Signature`]: ../../../../sequoia_openpgp/packet/enum.Signature.html
 #[crate::ffi_wrapper_type(prefix = "pgp_",
                      derive = "Clone, Debug, PartialEq, Parse, Serialize")]
 pub struct Signature(openpgp::packet::Signature);
diff --git a/openpgp-ffi/src/packet_pile.rs b/openpgp-ffi/src/packet_pile.rs
index 27a6b40a..1fef7bb8 100644
--- a/openpgp-ffi/src/packet_pile.rs
+++ b/openpgp-ffi/src/packet_pile.rs
@@ -3,7 +3,7 @@
 //!
 //! Wraps [`sequoia-openpgp::PacketPile`].
 //!
-//! [`sequoia-openpgp::PacketPile`]: ../../sequoia_openpgp/struct.PacketPile.html
+//! [`sequoia-openpgp::PacketPile`]: ../../../sequoia_openpgp/struct.PacketPile.html
 
 extern crate sequoia_openpgp as openpgp;
 
@@ -11,7 +11,7 @@ extern crate sequoia_openpgp as openpgp;
 ///
 /// Wraps [`sequoia-openpgp::PacketPile`].
 ///
-/// [`sequoia-openpgp::PacketPile`]: ../../sequoia_openpgp/struct.PacketPile.html
+/// [`sequoia-openpgp::PacketPile`]: ../../../sequoia_openpgp/struct.PacketPile.html
 #[crate::ffi_wrapper_type(prefix = "pgp_",
                      derive = "Clone, Debug, PartialEq, Parse, Serialize")]
 pub struct PacketPile(openpgp::PacketPile);
diff --git a/openpgp-ffi/src/parse/mod.rs b/openpgp-ffi/src/parse/mod.rs
index a4f213b5..a2569b2b 100644
--- a/openpgp-ffi/src/parse/mod.rs
+++ b/openpgp-ffi/src/parse/mod.rs
@@ -3,8 +3,8 @@
 //! Wraps [`sequoia-openpgp::parse::PacketParser`] and [related
 //! functionality].
 //!
-//! [`sequoia-openpgp::parse::PacketParser`]: ../../sequoia_openpgp/parse/struct.PacketParser.html
-//! [related functionality]: ../../sequoia_openpgp/parse/index.html
+//! [`sequoia-openpgp::parse::PacketParser`]: ../../../sequoia_openpgp/parse/struct.PacketParser.html
+//! [related functionality]: ../../../sequoia_openpgp/parse/index.html
 
 use std::mem::forget;
 use std::ptr;
@@ -140,7 +140,7 @@ pub extern "C" fn pgp_packet_parser_recursion_depth
 /// recurse into the container, but skips any packets it contains.
 /// To recurse into the container, use the [`recurse()`] method.
 ///
-///   [`PacketParsererBuilder`]: ../../sequoia_openpgp/parse/struct.PacketParserBuilder.html
+///   [`PacketParsererBuilder`]: ../../../sequoia_openpgp/parse/struct.PacketParserBuilder.html
 ///   [`recurse()`]: fn.pgp_packet_parser_recurse.html
 ///
 /// The return value is a tuple containing:
diff --git a/openpgp-ffi/src/parse/stream.rs b/openpgp-ffi/src/parse/stream.rs
index 76d19785..ae3fde7a 100644
--- a/openpgp-ffi/src/parse/stream.rs
+++ b/openpgp-ffi/src/parse/stream.rs
@@ -8,7 +8,7 @@
 //! Wraps the streaming parsing functions, see
 //! [`sequoia-openpgp::parse::stream`].
 //!
-//! [`sequoia-openpgp::parse::stream`]: ../../../sequoia_openpgp/parse/stream/index.html
+//! [`sequoia-openpgp::parse::stream`]: ../../../../sequoia_openpgp/parse/stream/index.html
 
 use std::ptr;
 use libc::{c_int, c_void, time_t};
diff --git a/openpgp-ffi/src/serialize.rs b/openpgp-ffi/src/serialize.rs
index d6a7695b..db9e708a 100644
--- a/openpgp-ffi/src/serialize.rs
+++ b/openpgp-ffi/src/serialize.rs
@@ -3,7 +3,7 @@
 //! Wraps the streaming packet serialization, see
 //! [`sequoia-openpgp::serialize::stream`].
 //!
-//! [`sequoia-openpgp::serialize::stream`]: ../../sequoia_openpgp/serialize/stream/index.html
+//! [`sequoia-openpgp::serialize::stream`]: ../../../sequoia_openpgp/serialize/stream/index.html
 
 use std::ptr;
 use std::slice;
@@ -237,7 +237,7 @@ pub extern "C" fn pgp_literal_writer_new
 ///
 /// Wraps [`sequoia-openpgp::serialize::stream::Recipient`].
 ///
-/// [`sequoia-openpgp::serialize::stream::Recipient`]: ../../sequoia_openpgp/serialize/stream/struct.Recipient.html
+/// [`sequoia-openpgp::serialize::stream::Recipient`]: ../../../sequoia_openpgp/serialize/stream/struct.Recipient.html
 #[crate::ffi_wrapper_type(prefix = "pgp_", derive = "Debug")]
 pub struct Recipient<'a>(openpgp::serialize::stream::Recipient<'a>);
 
diff --git a/openpgp-ffi/src/tsk.rs b/openpgp-ffi/src/tsk.rs
index 2d1351ad..bc4307ef 100644
--- a/openpgp-ffi/src/tsk.rs
+++ b/openpgp-ffi/src/tsk.rs
@@ -1,8 +1,8 @@
 //! Transferable secret keys.
 //!
-//! Wraps [`sequoia-openpgp::cert::TSK`].
+//! Wraps [`sequoia-openpgp::serialize::TSK`].
 //!
-//! [`sequoia-openpgp::cert::TSK`]: ../../sequoia_openpgp/struct.TSK.html
+//! [`sequoia-openpgp::serialize::TSK`]: ../../../sequoia_openpgp/serialize/struct.TSK.html
 
 extern crate sequoia_openpgp as openpgp;
 
@@ -13,8 +13,8 @@ extern crate sequoia_openpgp as openpgp;
 ///
 /// [RFC 4880, section 11.2]: https://tools.ietf.org/html/rfc4880#section-11.2
 ///
-/// Wraps [`sequoia-openpgp::cert::TSK`].
+/// Wraps [`sequoia-openpgp::serialize::TSK`].
 ///
-/// [`sequoia-openpgp::cert::TSK`]: ../../sequoia_openpgp/enum.TSK.html
+/// [`sequoia-openpgp::serialize::TSK`]: ../../../sequoia_openpgp/serialize/struct.TSK.html
 #[crate::ffi_wrapper_type(prefix = "pgp_", name = "tsk", derive = "Serialize")]
 pub struct TSK<'a>(openpgp::serialize::TSK<'a>);
diff --git a/openpgp/src/packet/header/ctb.rs b/openpgp/src/packet/header/ctb.rs
index b28b2311..7ee1d24c 100644
--- a/openpgp/src/packet/header/ctb.rs
+++ b/openpgp/src/packet/header/ctb.rs
@@ -170,8 +170,8 @@ impl CTBOld {
 /// There are two CTB variants: the [old CTB format] and the [new CTB
 /// format].
 ///
-///   [old CTB format]: ./CTBOld.t.html
-///   [new CTB format]: ./CTBNew.t.html
+///   [old CTB format]: struct.CTBOld.html
+///   [new CTB format]: struct.CTBNew.html
 ///
 /// Note: CTB stands for Cipher Type Byte.
 #[derive(Clone, Debug)]
diff --git a/openpgp/src/packet/signature/subpacket.rs b/openpgp/src/packet/signature/subpacket.rs
index 1e0b9ad6..3d87f600 100644
--- a/openpgp/src/packet/signature/subpacket.rs
+++ b/openpgp/src/packet/signature/subpacket.rs
@@ -20,10 +20,10 @@
 //! changes by indicating whether it is safe to ignore an unknown
 //! subpacket or notation.
 //!
-//! A number of methods are defined on the [`Signature`] struct for
-//! working with subpackets.
+//! A number of methods are defined on [`Signature`] for working with
+//! subpackets.
 //!
-//! [`Signature`]: ../struct.Signature.html
+//! [`Signature`]: ../../enum.Signature.html
 //!
 //! # Examples
 //!
diff --git a/openpgp/src/serialize/cert.rs b/openpgp/src/serialize/cert.rs
index 4c217cbf..cad18c63 100644
--- a/openpgp/src/serialize/cert.rs
+++ b/openpgp/src/serialize/cert.rs
@@ -262,7 +262,7 @@ impl Cert {
     ///
     /// This object writes out secret keys during serialization.
     ///
-    /// [`TSK`]: serialize/struct.TSK.html
+    /// [`TSK`]: ../serialize/struct.TSK.html
     pub fn as_tsk<'a>(&'a self) -> TSK<'a> {
         TSK::new(self)
     }
@@ -275,7 +275,7 @@ impl Cert {
 /// create a `TSK`, which is a shim on top of the `Cert`, and serialize
 /// this.
 ///
-/// [`Cert::as_tsk()`]: ../struct.Cert.html#method.as_tsk
+/// [`Cert::as_tsk()`]: ../cert/struct.Cert.html#method.as_tsk
 ///
 /// # Example
 /// ```
diff --git a/openpgp/src/serialize/mod.rs b/openpgp/src/serialize/mod.rs
index 3d74aa4f..66a46230 100644
--- a/openpgp/src/serialize/mod.rs
+++ b/openpgp/src/serialize/mod.rs
@@ -309,8 +309,8 @@ impl Serialize for BodyLength {
     /// [`BodyLength::Indeterminate`].  If you want to serialize an
     /// old-style length, use [`serialize_old(..)`].
     ///
-    /// [`Error::InvalidArgument`]: ../enum.Error.html#variant.InvalidArgument
-    /// [`BodyLength::Indeterminate`]: ../packet/enum.BodyLength.html#variant.Indeterminate
+    /// [`Error::InvalidArgument`]: ../../enum.Error.html#variant.InvalidArgument
+    /// [`BodyLength::Indeterminate`]: #variant.Indeterminate
     /// [`serialize_old(..)`]: #method.serialize_old
     fn serialize(&self, o: &mut dyn std::io::Write) -> Result<()> {
         match self {
@@ -387,8 +387,8 @@ impl BodyLength {
     /// [`BodyLength::Partial`].  If you want to serialize a
     /// new-style length, use [`serialize(..)`].
     ///
-    /// [`Error::InvalidArgument`]: ../enum.Error.html#variant.InvalidArgument
-    /// [`BodyLength::Partial`]: ../packet/enum.BodyLength.html#variant.Partial
+    /// [`Error::InvalidArgument`]: ../../enum.Error.html#variant.InvalidArgument
+    /// [`BodyLength::Partial`]: #variant.Partial
     /// [`serialize(..)`]: #impl-Serialize
     pub fn serialize_old<W: io::Write>(&self, o: &mut W) -> Result<()> {
         // Assume an optimal encoding is desired.