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diff --git a/docs/reference/src/api/msg/index.md b/docs/reference/src/api/msg/index.md
new file mode 100644
index 00000000..1a7bdabf
--- /dev/null
+++ b/docs/reference/src/api/msg/index.md
@@ -0,0 +1,96 @@
+# Messages
+
+Messages in Scalability Protocols are the fundamental unit of transmission
+and reception,
+as these protocols are fundamentally message-oriented.
+
+## {{i: Message object}}
+
+An `nng_msg` represents a single {{i:message}} sent between Scalability Protocols peers.
+
+Messages have a {{i:body}}, containing the application supplied
+payload, and a {{i:header}}, containing protocol specific routing and similar
+related information.
+
+> [!TIP]
+> Only applications using [raw](../../overview/raw.md) mode need to
+> access the message header.
+
+### Creating, Destroying and Using
+
+Messages are allocated using [`nng_msg_alloc()`](nng_msg_alloc.md),
+and are deallocated using [`nng_msg_free()`](nng_msg_free.md).
+
+In addition there are other functions used to access message contents,
+including adding data to either the beginning or end of the message,
+automatic data conversion, and removing data from the beginning or end.
+
+### Performance Considerations
+
+While there are convenience wrappers for sending and receiving arrays of
+bytes, using message objects directly when possible will give better
+performance by reducing data copies and needless allocations.
+
+These functions are designed to try to avoid copying message contents
+by making use of scratch areas at the beginning and end of the message.
+These scratch areas, the "headroom" and "tailroom", are automatically
+included when allocating a message.
+
+### Direct Use Forbidden
+
+The `nng_msg` structure is opaque, and applications should never try to
+rely on the size of it, nor access internal members directly.
+This insulates the application from changes in subsequent _NNG_ versions
+that would affect the binary representation of the `nng_msg` itself.
+
+## Examples
+
+### Example 1: Preparing a message for use
+
+```c
+#include <nng/nng.h>
+nng_msg *m;
+if (nng_msg_alloc(&m, strlen("content") + 1) != 0) {
+   // handle error
+}
+strcpy(nng_msg_body(m), "content");
+```
+
+### Example 2: Preallocating message content
+
+```c
+if (nng_msg_alloc(&m, 1024) != 0) {
+    // handle error
+}
+while ((val64 = next_datum()) != 0) P
+    if (nng_msg_append_u64(m, val64) != 0) {
+        // handle error
+    }
+}
+```
+
+## See Also
+
+[nng_aio_get_msg](../aio/nng_aio_get_msg.md),
+[nng_aio_set_msg](../aio/nng_aio_set_msg.md),
+[nng_msg_alloc](nng_msg_alloc.md),
+[nng_msg_append](nng_msg_append.md),
+[nng_msg_body](nng_msg_body.md),
+[nng_msg_capacity](nng_msg_capacity.md),
+[nng_msg_dup](nng_msg_dup.md),
+[nng_msg_free](nng_msg_free.md),
+[nng_msg_header](nng_msg_header.md),
+[nng_msg_header_append](nng_msg_header_append.md),
+[nng_msg_header_chop](nng_msg_header_chop.md),
+[nng_msg_header_clear](nng_msg_header_clear.md),
+[nng_msg_header_insert](nng_msg_header_insert.md),
+[nng_msg_header_len](nng_msg_header_len.md),
+[nng_msg_header_trim](nng_msg_header_trim.md),
+[nng_msg_insert](nng_msg_insert.md),
+[nng_msg_len](nng_msg_len.md),
+[nng_msg_reserve](nng_msg_reserve.md),
+[nng_msg_realloc](nng_msg_realloc.md),
+[nng_msg_set_pipe](nng_msg_set_pipe.md),
+[nng_msg_trim](nng_msg_trim.md),
+[nng_recvmsg](../socket/nng_recvmsg.md),
+[nng_sendmsg](../socket/nng_sendmsg.md)
diff --git a/docs/reference/src/api/msg/nng_msg_alloc.md b/docs/reference/src/api/msg/nng_msg_alloc.md
new file mode 100644
index 00000000..163d193b
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_alloc.md
@@ -0,0 +1,40 @@
+# nng_msg_alloc
+
+## NAME
+
+nng_msg_alloc --- allocate a message
+
+## SYNOPSIS
+
+```c
+#include <nng/nng.h>
+
+int nng_msg_alloc(nng_msg **msgp, size_t size);
+```
+
+## DESCRIPTION
+
+The `nng_msg_alloc()` function allocates a new message with body length _size_
+and stores the result in _msgp_.
+Messages allocated with this function contain a body and optionally a header.
+They are used with receive and transmit functions.
+
+## RETURN VALUES
+
+This function returns 0 on success, and non-zero otherwise.
+
+## ERRORS
+
+- `NNG_ENOMEM`: Insufficient free memory exists to allocate a message.
+
+## SEE ALSO
+
+[nng_msg_free](nng_msg_free.md),
+[nng_msg_body](nng_msg_body.md),
+[nng_msg_dup](nng_msg_dup.md),
+[nng_msg_header](nng_msg_header.md),
+[nng_msg_header_len](nng_msg_header_len.md),
+[nng_msg_len](nng_msg_len.md),
+[nng_msg_capacity](nng_msg_capacity.md),
+[nng_msg_reserve](nng_msg_reserve.md),
+[nng_msg_realloc](nng_msg_realloc.md)
diff --git a/docs/reference/src/api/msg/nng_msg_append.md b/docs/reference/src/api/msg/nng_msg_append.md
new file mode 100644
index 00000000..5807d3a6
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_append.md
@@ -0,0 +1,46 @@
+# nng_msg_append
+
+## NAME
+
+nng_msg_append --- append to message body
+
+## SYNOPSIS
+
+```c
+#include <nng/nng.h>
+
+int nng_msg_append(nng_msg *msg, const void *val, size_t size);
+int nng_msg_append_u16(nng_msg *msg, uint16_t val16);
+int nng_msg_append_u32(nng_msg *msg, uint32_t val32);
+int nng_msg_append_u64(nng_msg *msg, uint64_t val64);
+```
+
+## DESCRIPTION
+
+The `nng_msg_append()` family of functions appends data to
+the end of the body of message _msg_, reallocating it if necessary.
+The first function appends _size_ bytes, copying them from _val_.
+The remaining functions append the value specified (such as _val32_) in
+network-byte order (big-endian).
+
+## RETURN VALUES
+
+These functions return 0 on success, and non-zero otherwise.
+
+## ERRORS
+
+- `NNG_ENOMEM`: Insufficient free memory exists.
+
+## SEE ALSO
+
+[nng_msg_alloc](nng_msg_alloc.md),
+[nng_msg_body](nng_msg_body.md),
+[nng_msg_capacity](nng_msg_capacity.md),
+[nng_msg_chop](nng_msg_chop.md),
+[nng_msg_clear](nng_msg_chop.md),
+[nng_msg_free](nng_msg_free.md),
+[nng_msg_insert](nng_msg_insert.md),
+[nng_msg_len](nng_msg_len.md),
+[nng_msg_reserve](nng_msg_reserve.md),
+[nng_msg_realloc](nng_msg_realloc.md),
+[nng_msg_trim](nng_msg_trim.md)
diff --git a/docs/reference/src/api/msg/nng_msg_body.md b/docs/reference/src/api/msg/nng_msg_body.md
new file mode 100644
index 00000000..abd49c7f
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_body.md
@@ -0,0 +1,47 @@
+# nng_msg_body
+
+## NAME
+
+nng_msg_body --- return message body
+
+## SYNOPSIS
+
+```c
+#include <nng/nng.h>
+
+void *nng_msg_body(nng_msg *msg);
+```
+
+## DESCRIPTION
+
+The `nng_msg_body()` function returns a pointer to the start of the body
+content of the message _msg_.
+
+> [!NOTE]
+> The value returned by this is invalidated by a call to any of the
+> functions that modify the message itself.
+> Such functions are
+> [`nng_msg_free()`](nng_msg_free.md),
+> [`nng_msg_realloc()`](nng_msg_realloc.md),
+> any of the [`nng_msg_trim()`](nng_msg_trim.md),
+> [`nng_msg_chop()`](nng_msg_chop.md),
+> [`nng_msg_append()`](nng_msg_append.md),
+> or [`nng_msg_insert()`](nng_msg_insert.md) variants.
+
+## RETURN VALUES
+
+Pointer to start of message body.
+
+## SEE ALSO
+
+[nng_msg_alloc](nng_msg_alloc.md),
+[nng_msg_append](nng_msg_append.md),
+[nng_msg_capacity](nng_msg_capacity.md),
+[nng_msg_chop](nng_msg_chop.md),
+[nng_msg_clear](nng_msg_clear.md),
+[nng_msg_free](nng_msg_free.md),
+[nng_msg_insert](nng_msg_insert.md),
+[nng_msg_len](nng_msg_len.md),
+[nng_msg_reserve](nng_msg_reserve.md),
+[nng_msg_realloc](nng_msg_realloc.md),
+[nng_msg_trim](nng_msg_trim.md)
diff --git a/docs/reference/src/api/msg/nng_msg_capacity.md b/docs/reference/src/api/msg/nng_msg_capacity.md
new file mode 100644
index 00000000..707a04e3
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_capacity.md
@@ -0,0 +1,30 @@
+# nng_msg_capacity
+
+## NAME
+
+nng_msg_capacity --- return message body length
+
+## SYNOPSIS
+
+```c
+#include <nng/nng.h>
+
+size_t nng_msg_capacity(nng_msg *msg);
+```
+
+## DESCRIPTION
+
+The `nng_msg_capacity()` returns the storage allocated for the body of message _msg_.
+The capacity includes the current contents of the message and free space after it.
+The message body may grow to capacity without performing any further allocations.
+
+## RETURN VALUES
+
+Allocated capacity for message body.
+
+## SEE ALSO
+
+[nng_msg_alloc](nng_msg_alloc.md),
+[nng_msg_realloc](nng_msg_realloc.md),
+[nng_msg_reserve](nng_msg_reserve.md)
+[nng_msg_body](nng_msg_body.md)
diff --git a/docs/reference/src/api/msg/nng_msg_chop.md b/docs/reference/src/api/msg/nng_msg_chop.md
new file mode 100644
index 00000000..fc9a0df5
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_chop.md
@@ -0,0 +1,47 @@
+# nng_msg_chop
+
+## NAME
+
+nng_msg_chop --- remove data from end of message body
+
+## SYNOPSIS
+
+```c
+#include <nng/nng.h>
+
+int nng_msg_chop(nng_msg *msg, size_t size);
+int nng_msg_chop_u16(nng_msg *msg, uint16_t *val16);
+int nng_msg_chop_u32(nng_msg *msg, uint32_t *val32);
+int nng_msg_chop_u64(nng_msg *msg, uint64_t *val64);
+```
+
+## DESCRIPTION
+
+The `nng_msg_chop()` family of functions removes data from
+the end of the body of message _msg_.
+The first function removes _size_ bytes.
+The remaining functions remove 2, 4, or 8 bytes, and stores them in the value
+(such as _val32_),
+after converting them from network-byte order (big-endian) to native byte order.
+
+## RETURN VALUES
+
+These functions return 0 on success, and non-zero otherwise.
+
+## ERRORS
+
+- `NNG_EINVAL`: The message body is too short to remove the requested data.
+
+## SEE ALSO
+
+[nng_msg_alloc](nng_msg_alloc.md),
+[nng_msg_append](nng_msg_alloc.md),
+[nng_msg_body](nng_msg_body.md),
+[nng_msg_capacity](nng_msg_capacity.md),
+[nng_msg_clear](nng_msg_chop.md),
+[nng_msg_free](nng_msg_free.md),
+[nng_msg_insert](nng_msg_insert.md),
+[nng_msg_len](nng_msg_len.md),
+[nng_msg_reserve](nng_msg_reserve.md),
+[nng_msg_realloc](nng_msg_realloc.md),
+[nng_msg_trim](nng_msg_trim.md)
diff --git a/docs/reference/src/api/msg/nng_msg_clear.md b/docs/reference/src/api/msg/nng_msg_clear.md
new file mode 100644
index 00000000..af25c072
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_clear.md
@@ -0,0 +1,23 @@
+# nng_msg_clear
+
+## NAME
+
+nng_msg_clear --- clear message body content
+
+## SYNOPSIS
+
+```c
+#include <nng/nng.h>
+
+void nng_msg_clear(nng_msg *msg);
+```
+
+## DESCRIPTION
+
+The `nng_msg_clear()` function resets the body length of _msg_ to zero.
+
+## SEE ALSO
+
+[nng_msg_alloc](nng_msg_alloc.md),
+[nng_msg_capacity](nng_msg_capacity.md),
+[nng_msg_reserve](nng_msg_reserve.md)
diff --git a/docs/reference/src/api/msg/nng_msg_dup.md b/docs/reference/src/api/msg/nng_msg_dup.md
new file mode 100644
index 00000000..dae376e8
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_dup.md
@@ -0,0 +1,34 @@
+# nng_msg_dup
+
+## NAME
+
+nng_msg_dup --- duplicate a message
+
+## SYNOPSIS
+
+```c
+#include <nng/nng.h>
+
+int nng_msg_dup(nng_msg **dup, nng_msg_t *orig);
+```
+
+## DESCRIPTION
+
+The `nng_msg_dup()` makes a duplicate of the original message _orig_, and
+saves the result in the location pointed by _dup_.
+The actual message body and header content is copied,
+but the duplicate may contain a
+different amount of unused space than the original message.
+
+## RETURN VALUES
+
+This function returns 0 on success, and non-zero otherwise.
+
+## ERRORS
+
+- `NNG_ENOMEM`: Insufficient free memory exists to duplicate a message.
+
+## SEE ALSO
+
+[nng_msg_alloc](nng_msg_alloc.md),
+[nng_msg_free](nng_msg_free.md)
diff --git a/docs/reference/src/api/msg/nng_msg_free.md b/docs/reference/src/api/msg/nng_msg_free.md
new file mode 100644
index 00000000..94887be0
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_free.md
@@ -0,0 +1,22 @@
+# nng_msg_free
+
+## NAME
+
+nng_msg_free --- free a message
+
+## SYNOPSIS
+
+```c
+#include <nng/nng.h>
+
+void nng_msg_free(nng_msg *msg);
+```
+
+## DESCRIPTION
+
+The `nng_msg_free()` function deallocates the message _msg_ entirely.
+
+## SEE ALSO
+
+[nng_msg_alloc](nng_msg_alloc.md),
+[nng_msg_realloc](nng_msg_realloc.md)
diff --git a/docs/reference/src/api/msg/nng_msg_get_pipe.3.adoc b/docs/reference/src/api/msg/nng_msg_get_pipe.3.adoc
new file mode 100644
index 00000000..154f4c43
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_get_pipe.3.adoc
@@ -0,0 +1,60 @@
+= nng_msg_get_pipe(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_msg_get_pipe - get pipe for message
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+nng_pipe nng_msg_get_pipe(nng_msg *msg);
+----
+
+== DESCRIPTION
+
+The `nng_msg_get_pipe()` returns the xref:nng_pipe.5.adoc[`nng_pipe`] object
+associated with message _msg_.
+On receive, this is the pipe from which a message was received.
+On transmit, this would be the pipe that the message should be delivered
+to, if a specific peer is required.
+
+NOTE: Not all protocols support overriding the destination pipe.
+
+The most usual use case for this is to obtain information about the peer
+from which the message was received.
+This can be used to provide different behaviors for different peers, such as
+a higher level of authentication for peers located on an untrusted network.
+The xref:nng_pipe_getopt.3.adoc[`nng_pipe_getopt()`] function
+is useful in this situation.
+
+
+== RETURN VALUES
+
+This function returns the pipe associated with this message, which will
+be a positive value.
+If the pipe is non-positive, then that indicates that
+no specific pipe is associated with the message.
+
+== ERRORS
+
+None.
+
+== SEE ALSO
+
+[.text-left]
+xref:nng_msg_alloc.3.adoc[nng_msg_alloc(3)],
+xref:nng_msg_set_pipe.3.adoc[nng_msg_set_pipe(3)],
+xref:nng_pipe_getopt.3.adoc[nng_pipe_getopt(3)],
+xref:nng.7.adoc[nng(7)]
diff --git a/docs/reference/src/api/msg/nng_msg_header.3.adoc b/docs/reference/src/api/msg/nng_msg_header.3.adoc
new file mode 100644
index 00000000..eac45ffd
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_header.3.adoc
@@ -0,0 +1,58 @@
+= nng_msg_header(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_msg_header - return message header
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+void *nng_msg_header(nng_msg *msg);
+----
+
+== DESCRIPTION
+
+The `nng_msg_header()` function returns a pointer to the start of the header
+content of the message _msg_.
+
+NOTE: The message header contains protocol-specific header content.  Most
+applications should not need to access this content, but it is available
+for raw mode sockets (set with the
+xref:nng_options.5.adoc#NNG_OPT_RAW[`NNG_OPT_RAW`] option.)
+
+NOTE: The value returned by this is invalidated by a call to any of the
+functions that modify the message or the header content.
+
+== RETURN VALUES
+
+Pointer to start of message header.
+
+== ERRORS
+
+None.
+
+== SEE ALSO
+
+[.text-left]
+xref:nng_msg_alloc.3.adoc[nng_msg_alloc(3)],
+xref:nng_msg_body.3.adoc[nng_msg_body(3)],
+xref:nng_msg_free.3.adoc[nng_msg_free(3)],
+xref:nng_msg_header_append.3.adoc[nng_msg_header_append(3)],
+xref:nng_msg_header_chop.3.adoc[nng_msg_header_chop(3)],
+xref:nng_msg_header_insert.3.adoc[nng_msg_header_insert(3)]
+xref:nng_msg_header_len.3.adoc[nng_msg_header_len(3)],
+xref:nng_msg_header_trim.3.adoc[nng_msg_header_trim(3)],
+xref:nng_msg.5.adoc[nng_msg(5)],
+xref:nng.7.adoc[nng(7)]
diff --git a/docs/reference/src/api/msg/nng_msg_header_append.3.adoc b/docs/reference/src/api/msg/nng_msg_header_append.3.adoc
new file mode 100644
index 00000000..16badf0b
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_header_append.3.adoc
@@ -0,0 +1,58 @@
+= nng_msg_header_append(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_msg_header_append - append to message header
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+int nng_msg_header_append(nng_msg *msg, const void *val, size_t size);
+int nng_msg_header_append_u16(nng_msg *msg, uint16_t val16);
+int nng_msg_header_append_u32(nng_msg *msg, uint32_t val32);
+int nng_msg_header_append_u64(nng_msg *msg, uint64_t val64);
+----
+
+== DESCRIPTION
+
+The `nng_msg_header_append()` family of functions appends data to
+the end of the headers of message _msg_, reallocating it if necessary.
+The first function appends _size_ bytes, copying them from _val_.
+
+The remaining functions append the value (such as _val32_) in
+network-byte order (big-endian).
+
+
+== RETURN VALUES
+
+These functions return 0 on success, and non-zero otherwise.
+
+== ERRORS
+
+[horizontal]
+`NNG_ENOMEM`:: Insufficient free memory exists.
+
+== SEE ALSO
+
+[.text-left]
+xref:nng_msg_alloc.3.adoc[nng_msg_alloc(3)],
+xref:nng_msg_header.3.adoc[nng_msg_header(3)],
+xref:nng_msg_header_chop.3.adoc[nng_msg_header_chop(3)],
+xref:nng_msg_header_insert.3.adoc[nng_msg_header_insert(3)],
+xref:nng_msg_header_len.3.adoc[nng_msg_header_len(3)],
+xref:nng_msg_header_trim.3.adoc[nng_msg_header_trim(3)],
+xref:nng_msg_free.3.adoc[nng_msg_free(3)],
+xref:nng_strerror.3.adoc[nng_strerror(3)],
+xref:nng.7.adoc[nng(7)]
diff --git a/docs/reference/src/api/msg/nng_msg_header_chop.3.adoc b/docs/reference/src/api/msg/nng_msg_header_chop.3.adoc
new file mode 100644
index 00000000..454e9e51
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_header_chop.3.adoc
@@ -0,0 +1,58 @@
+= nng_msg_header_chop(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_msg_header_chop - remove data from end of message header
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+int nng_msg_header_chop(nng_msg *msg, size_t size);
+int nng_msg_header_chop_u16(nng_msg *msg, uint16_t *val16);
+int nng_msg_header_chop_u32(nng_msg *msg, uint32_t *val32);
+int nng_msg_header_chop_u64(nng_msg *msg, uint64_t *val64);
+----
+
+== DESCRIPTION
+
+The `nng_msg_header_chop()` family of functions removes
+data from the end of the header of message _msg_.
+The first function removes _size_ bytes.
+The remaining functions remove 2, 4, or 8 bytes, and stores them in the value
+(such as _val32_),
+after converting them from network-byte order (big-endian) to native
+byte order.
+
+== RETURN VALUES
+
+These function return 0 on success, and non-zero otherwise.
+
+== ERRORS
+
+[horizontal]
+`NNG_EINVAL`:: The message header is too short to remove the requested data.
+
+== SEE ALSO
+
+[.text-left]
+xref:nng_msg_alloc.3.adoc[nng_msg_alloc(3)],
+xref:nng_msg_header.3.adoc[nng_msg_header(3)],
+xref:nng_msg_header_append.3.adoc[nng_msg_header_append(3)],
+xref:nng_msg_header_insert.3.adoc[nng_msg_header_insert(3)],
+xref:nng_msg_header_len.3.adoc[nng_msg_header_len(3)],
+xref:nng_msg_header_trim.3.adoc[nng_msg_header_trim(3)],
+xref:nng_msg_free.3.adoc[nng_msg_free(3)],
+xref:nng_strerror.3.adoc[nng_strerror(3)],
+xref:nng.7.adoc[nng(7)]
diff --git a/docs/reference/src/api/msg/nng_msg_header_clear.3.adoc b/docs/reference/src/api/msg/nng_msg_header_clear.3.adoc
new file mode 100644
index 00000000..d00286ed
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_header_clear.3.adoc
@@ -0,0 +1,42 @@
+= nng_msg_header_clear(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_msg_header_clear - clear message header
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+void nng_msg_header_clear(nng_msg *msg);
+----
+
+== DESCRIPTION
+
+The `nng_msg_clear()` function resets the header length of _msg_ to zero.
+
+== RETURN VALUES
+
+None.
+
+== ERRORS
+
+None.
+
+== SEE ALSO
+
+[.text-left]
+xref:nng_msg_alloc.3.adoc[nng_msg_alloc(3)],
+xref:nng_msg_free.3.adoc[nng_msg_free(3)],
+xref:nng.7.adoc[nng(7)]
diff --git a/docs/reference/src/api/msg/nng_msg_header_insert.3.adoc b/docs/reference/src/api/msg/nng_msg_header_insert.3.adoc
new file mode 100644
index 00000000..a2bf0d63
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_header_insert.3.adoc
@@ -0,0 +1,60 @@
+= nng_msg_header_insert(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_msg_header_insert - prepend to message header
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+int nng_msg_header_insert(nng_msg *msg, const void *val, size_t size);
+int nng_msg_header_insert_u16(nng_msg *msg, uint16_t val16);
+int nng_msg_header_insert_u32(nng_msg *msg, uint32_t val32);
+int nng_msg_header_insert_u64(nng_msg *msg, uint64_t val64);
+----
+
+== DESCRIPTION
+
+The `nng_msg_header_insert()` family of functions
+prepends data to the front of the headers of message _msg_, reallocating
+if necessary.
+The first function prepends _size_ bytes, copying them from _val_.
+The remaining functions prepend the specified value (such as _val32_) in
+network-byte order (big-endian).
+
+== RETURN VALUES
+
+These functions return 0 on success, and non-zero otherwise.
+
+== ERRORS
+
+[horizontal]
+`NNG_ENOMEM`:: Insufficient free memory exists.
+
+== SEE ALSO
+
+[.text-left]
+xref:nng_msg_alloc.3.adoc[nng_msg_alloc(3)],
+xref:nng_msg_header.3.adoc[nng_msg_header(3)],
+xref:nng_msg_header_append.3.adoc[nng_msg_header_append(3)],
+xref:nng_msg_header_chop.3.adoc[nng_msg_header_chop(3)],
+xref:nng_msg_header_len.3.adoc[nng_msg_header_len(3)],
+xref:nng_msg_header_trim.3.adoc[nng_msg_header_trim(3)],
+xref:nng_msg_free.3.adoc[nng_msg_free(3)],
+xref:nng_msg_capacity.3.adoc[nng_msg_capacity(3)],
+xref:nng_msg_reserve.3.adoc[nng_msg_reserve(3)],
+xref:nng_msg_realloc.3.adoc[nng_msg_realloc(3)],
+xref:nng_strerror.3.adoc[nng_strerror(3)],
+xref:nng.7.adoc[nng(7)]
diff --git a/docs/reference/src/api/msg/nng_msg_header_len.3.adoc b/docs/reference/src/api/msg/nng_msg_header_len.3.adoc
new file mode 100644
index 00000000..0a7b3613
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_header_len.3.adoc
@@ -0,0 +1,43 @@
+= nng_msg_header_len(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_msg_header_len - return message header length
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+size_t nng_msg_header_len(nng_msg *msg);
+----
+
+== DESCRIPTION
+
+The `nng_msg_header_len()` returns the length of message header of _msg_.
+
+== RETURN VALUES
+
+Length of message header.
+
+== ERRORS
+
+None.
+
+== SEE ALSO
+
+[.text-left]
+xref:nng_msg_alloc.3.adoc[nng_msg_alloc(3)],
+xref:nng_msg_header.3.adoc[nng_msg_header(3)],
+xref:nng_msg.5.adoc[nng_msg(5)],
+xref:nng.7.adoc[nng(7)]
diff --git a/docs/reference/src/api/msg/nng_msg_header_trim.3.adoc b/docs/reference/src/api/msg/nng_msg_header_trim.3.adoc
new file mode 100644
index 00000000..6df504ff
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_header_trim.3.adoc
@@ -0,0 +1,59 @@
+= nng_msg_header_trim(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_msg_header_trim - remove data from start of message header
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+int nng_msg_header_trim(nng_msg *msg, size_t size);
+int nng_msg_header_trim_u16(nng_msg *msg, uint16_t *val16);
+int nng_msg_header_trim_u32(nng_msg *msg, uint32_t *val32);
+int nng_msg_header_trim_u64(nng_msg *msg, uint64_t *val64);
+----
+
+== DESCRIPTION
+
+The `nng_msg_header_trim()` family of functions remove
+data from the start of the header of message _msg_.
+The first function removes _size_ bytes.
+The remaining functions removes 2, 4, or 8 bytes, and stores them in the
+value (such as _val32_),
+after converting them from network-byte order (big-endian) to native
+byte order.
+
+== RETURN VALUES
+
+This function returns 0 on success, and non-zero otherwise.
+
+== ERRORS
+
+[horizontal]
+`NNG_EINVAL`:: The message header is too short to remove the requested data.
+
+== SEE ALSO
+
+[.text-left]
+xref:nng_msg_alloc.3.adoc[nng_msg_alloc(3)],
+xref:nng_msg_header.3.adoc[nng_msg_header(3)],
+xref:nng_msg_header_append.3.adoc[nng_msg_header_append(3)],
+xref:nng_msg_header_chop.3.adoc[nng_msg_header_chop(3)],
+xref:nng_msg_header_insert.3.adoc[nng_msg_header_insert(3)],
+xref:nng_msg_header_len.3.adoc[nng_msg_header_len(3)],
+xref:nng_msg_free.3.adoc[nng_msg_free(3)],
+xref:nng_strerror.3.adoc[nng_strerror(3)],
+xref:nng_msg.5.adoc[nng_msg(5)],
+xref:nng.7.adoc[nng(7)]
diff --git a/docs/reference/src/api/msg/nng_msg_insert.3.adoc b/docs/reference/src/api/msg/nng_msg_insert.3.adoc
new file mode 100644
index 00000000..25f98fce
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_insert.3.adoc
@@ -0,0 +1,63 @@
+= nng_msg_insert(3)
+//
+// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_msg_insert - prepend to message body
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+int nng_msg_insert(nng_msg *msg, const void *val, size_t size);
+int nng_msg_insert_u16(nng_msg *msg, uint16_t val16);
+int nng_msg_insert_u32(nng_msg *msg, uint32_t val32);
+int nng_msg_insert_u64(nng_msg *msg, uint64_t val64);
+----
+
+== DESCRIPTION
+
+The `nng_msg_insert()` family of functions prepends data to
+the front of the body of message _msg_, reallocating it if necessary.
+The first function prepends _size_ bytes, copying them from _val_.
+The remaining functions prepend the specified value (such as _val32_)
+in network-byte order (big-endian).
+
+TIP: These functions make use of space pre-allocated in front of the
+message body if available, so they can often avoid performing any reallocation.
+Applications should use these instead of reallocating and copying message
+content themselves, in order to benefit from this capability.
+
+== RETURN VALUES
+
+These functions return 0 on success, and non-zero otherwise.
+
+== ERRORS
+
+[horizontal]
+`NNG_ENOMEM`:: Insufficient free memory exists.
+
+== SEE ALSO
+
+[.text-left]
+xref:nng_msg_alloc.3.adoc[nng_msg_alloc(3)],
+xref:nng_msg_append.3.adoc[nng_msg_append(3)],
+xref:nng_msg_body.3.adoc[nng_msg_body(3)],
+xref:nng_msg_chop.3.adoc[nng_msg_chop(3)],
+xref:nng_msg_free.3.adoc[nng_msg_free(3)],
+xref:nng_msg_len.3.adoc[nng_msg_len(3)],
+xref:nng_msg_realloc.3.adoc[nng_msg_realloc(3)],
+xref:nng_msg_trim.3.adoc[nng_msg_trim(3)],
+xref:nng_strerror.3.adoc[nng_strerror(3)],
+xref:nng_msg.5.adoc[nng_msg(5)],
+xref:nng.7.adoc[nng(7)]
diff --git a/docs/reference/src/api/msg/nng_msg_len.3.adoc b/docs/reference/src/api/msg/nng_msg_len.3.adoc
new file mode 100644
index 00000000..2a3dfe67
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_len.3.adoc
@@ -0,0 +1,43 @@
+= nng_msg_len(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_msg_len - return message body length
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+size_t nng_msg_len(nng_msg *msg);
+----
+
+== DESCRIPTION
+
+The `nng_msg_len()` returns the length of the body of message _msg_.
+
+== RETURN VALUES
+
+Length of message body.
+
+== ERRORS
+
+None.
+
+== SEE ALSO
+
+[.text-left]
+xref:nng_msg_alloc.3.adoc[nng_msg_alloc(3)],
+xref:nng_msg_body.3.adoc[nng_msg_body(3)],
+xref:nng_msg.5.adoc[nng_msg(5)],
+xref:nng.7.adoc[nng(7)]
diff --git a/docs/reference/src/api/msg/nng_msg_realloc.3.adoc b/docs/reference/src/api/msg/nng_msg_realloc.3.adoc
new file mode 100644
index 00000000..bf407289
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_realloc.3.adoc
@@ -0,0 +1,66 @@
+= nng_msg_realloc(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_msg_realloc - reallocate a message
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+int nng_msg_realloc(nng_msg *msg, size_t size);
+----
+
+== DESCRIPTION
+
+The `nng_msg_realloc()` function re-allocates a message so that it has
+a body of length _size_.
+This message attempts to avoid extra allocations,
+and will reuse the existing memory when possible.
+
+TIP: `nng_msg_realloc` is suitable for creating space for direct writing of data.
+When appending many small pieces of data to a message using xref:nng_msg_append.3.adoc[`nng_msg_append()`],
+allocations may be reduced by first using xref:nng_msg_reserve.3.adoc[`nng_msg_reserve()`]
+to create sufficient space.
+In any case, reallocating or appending to a message is guaranteed to succeed if the resulting
+body length is less than xref:nng_msg_capacity.3.adoc[`nng_msg_capacity()`]. 
+
+NOTE: Pointers to message body and header content obtained prior to this
+function must not be in use, as the underlying memory used for the message
+may have changed, particularly if the message size is increasing.
+
+== RETURN VALUES
+
+This function returns 0 on success, and non-zero otherwise.
+
+== ERRORS
+
+[horizontal]
+`NNG_ENOMEM`:: Insufficient free memory exists to reallocate a message.
+
+== SEE ALSO
+
+[.text-left]
+xref:nng_msg_reserve.3.adoc[nng_msg_reserve(3)],
+xref:nng_msg_alloc.3.adoc[nng_msg_alloc(3)],
+xref:nng_msg_append.3.adoc[nng_msg_append(3)],
+xref:nng_msg_body.3.adoc[nng_msg_body(3)],
+xref:nng_msg_chop.3.adoc[nng_msg_chop(3)],
+xref:nng_msg_free.3.adoc[nng_msg_free(3)],
+xref:nng_msg_insert.3.adoc[nng_msg_insert(3)],
+xref:nng_msg_len.3.adoc[nng_msg_len(3)],
+xref:nng_msg_trim.3.adoc[nng_msg_trim(3)],
+xref:nng_strerror.3.adoc[nng_strerror(3)],
+xref:nng_msg.5.adoc[nng_msg(5)],
+xref:nng.7.adoc[nng(7)]
diff --git a/docs/reference/src/api/msg/nng_msg_reserve.3.adoc b/docs/reference/src/api/msg/nng_msg_reserve.3.adoc
new file mode 100644
index 00000000..254c1e94
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_reserve.3.adoc
@@ -0,0 +1,63 @@
+= nng_msg_reserve(3)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_msg_reserve - reserve storage for a message
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+int nng_msg_reserve(nng_msg *msg, size_t capacity);
+----
+
+== DESCRIPTION
+
+The `nng_msg_reserve()` function ensures a message has allocated enough storage 
+to accommodate a body of the given length.
+This message attempts to avoid extra allocations,
+and will reuse the existing memory when possible.
+
+TIP: Using this message before xref:nng_msg_append.3.adoc[`nng_msg_append()`]
+will prevent additional memory allocations until the message's length exceeds
+the alotted capacity.
+
+NOTE: Pointers to message body and header content obtained prior to this
+function must not be in use, as the underlying memory used for the message
+may have changed, particularly if the message capacity is increasing.
+
+== RETURN VALUES
+
+This function returns 0 on success, and non-zero otherwise.
+
+== ERRORS
+
+[horizontal]
+`NNG_ENOMEM`:: Insufficient free memory exists to reallocate a message.
+
+== SEE ALSO
+
+[.text-left]
+xref:nng_msg_capacity.3.adoc[nng_msg_capacity(3)],
+xref:nng_msg_alloc.3.adoc[nng_msg_alloc(3)],
+xref:nng_msg_append.3.adoc[nng_msg_append(3)],
+xref:nng_msg_body.3.adoc[nng_msg_body(3)],
+xref:nng_msg_chop.3.adoc[nng_msg_chop(3)],
+xref:nng_msg_free.3.adoc[nng_msg_free(3)],
+xref:nng_msg_insert.3.adoc[nng_msg_insert(3)],
+xref:nng_msg_len.3.adoc[nng_msg_len(3)],
+xref:nng_msg_trim.3.adoc[nng_msg_trim(3)],
+xref:nng_strerror.3.adoc[nng_strerror(3)],
+xref:nng_msg.5.adoc[nng_msg(5)],
+xref:nng.7.adoc[nng(7)]
diff --git a/docs/reference/src/api/msg/nng_msg_set_pipe.3.adoc b/docs/reference/src/api/msg/nng_msg_set_pipe.3.adoc
new file mode 100644
index 00000000..c95cc83f
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_set_pipe.3.adoc
@@ -0,0 +1,50 @@
+= nng_msg_set_pipe(3)
+//
+// Copyright 2019 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_msg_set_pipe - set pipe for message
+
+== SYNOPSIS
+
+[source, c]
+----
+#include <nng/nng.h>
+
+void nng_msg_set_pipe(nng_msg *msg, nng_pipe p);
+----
+
+== DESCRIPTION
+
+The `nng_msg_set_pipe()` sets the pipe associated with message _m_ to _p_.
+This is most often useful when used with protocols that support directing
+a message to a specific peer.
+For example the xref:nng_pair.7.adoc[_pair_] version 1 protocol can do
+this when `NNG_OPT_PAIR1_POLY` mode is set.
+
+NOTE: Not all protocols support overriding the destination pipe.
+
+== RETURN VALUES
+
+None.
+
+== ERRORS
+
+None.
+
+== SEE ALSO
+
+[.text-left]
+xref:nng_msg_alloc.3.adoc[nng_msg_alloc(3)],
+xref:nng_msg_get_pipe.3.adoc[nng_msg_get_pipe(3)],
+xref:nng_pipe_getopt.3.adoc[nng_pipe_getopt(3)],
+xref:nng_msg.5.adoc[nng_msg(5)],
+xref:nng.7.adoc[nng(7)]
diff --git a/docs/reference/src/api/msg/nng_msg_trim.md b/docs/reference/src/api/msg/nng_msg_trim.md
new file mode 100644
index 00000000..c0b8f694
--- /dev/null
+++ b/docs/reference/src/api/msg/nng_msg_trim.md
@@ -0,0 +1,48 @@
+# nng_msg_trim
+
+## NAME
+
+nng_msg_trim --- remove data from start of message body
+
+## SYNOPSIS
+
+```c
+#include <nng/nng.h>
+
+int nng_msg_trim(nng_msg *msg, size_t size);
+int nng_msg_trim_u16(nng_msg *msg, uint16_t *val16);
+int nng_msg_trim_u32(nng_msg *msg, uint32_t *val32);
+int nng_msg_trim_u64(nng_msg *msg, uint64_t *val64);
+```
+
+## DESCRIPTION
+
+The `nng_msg_trim()` family of functions removes data from
+the start of the body of message _msg_.
+The first function removes _size_ bytes.
+The remaining functions remove 2, 4, or 8 bytes, and stores them in the value
+(such as _val32_),
+after converting them from network-byte order (big-endian) to native
+byte order.
+
+## RETURN VALUES
+
+These functions return 0 on success, and non-zero otherwise.
+
+## ERRORS
+
+- `NNG_EINVAL`: The message body is too short to remove the requested data.
+
+## SEE ALSO
+
+[nng_msg_alloc](nng_msg_alloc.md),
+[nng_msg_append](nng_msg_alloc.md),
+[nng_msg_body](nng_msg_body.md),
+[nng_msg_capacity](nng_msg_capacity.md),
+[nng_msg_chop](nng_msg_chop.md)
+[nng_msg_clear](nng_msg_chop.md),
+[nng_msg_free](nng_msg_free.md),
+[nng_msg_insert](nng_msg_insert.md),
+[nng_msg_len](nng_msg_len.md),
+[nng_msg_reserve](nng_msg_reserve.md),
+[nng_msg_realloc](nng_msg_realloc.md)