Move reference and blob stuff from atom extension to a separate "reference" extension.

5 files changed, 272 insertions, 200 deletions

diff --git a/ext/atom.lv2/atom.h b/ext/atom.lv2/atom.h
index 2895efd..d69c547 100644
--- a/ext/atom.lv2/atom.h
+++ b/ext/atom.lv2/atom.h
@@ -28,8 +28,7 @@
 #ifndef LV2_ATOM_H
 #define LV2_ATOM_H
 
-#define LV2_ATOM_URI         "http://lv2plug.in/ns/ext/atom"
-#define LV2_BLOB_SUPPORT_URI "http://lv2plug.in/ns/ext/atom#blobSupport"
+#define LV2_ATOM_URI "http://lv2plug.in/ns/ext/atom"
 
 #define LV2_ATOM_REFERENCE_TYPE 0
 
@@ -81,11 +80,6 @@ typedef struct _LV2_Atom {
 } LV2_Atom;
 
 /**
-   Reference, an LV2_Atom with type 0.
-*/
-typedef LV2_Atom LV2_Atom_Reference;
-
-/**
    The body of an atom:Literal.
 */
 typedef struct _LV2_Atom_Literal {
@@ -120,133 +114,4 @@ typedef struct _LV2_Object {
 	uint8_t  properties[]; /**< Sequence of LV2_Atom_Property */
 } LV2_Object;
 
-/* Optional Blob Support */
-
-/**
-   Dynamically Allocated LV2 Blob.
- 
-   This is an opaque blob of data of any type, dynamically allocated in memory.
-   Unlike an LV2_Atom, a blob is not necessarily POD. Plugins MUST only refer
-   to blobs via a Reference (an LV2_Atom with type 0), there is no way for a
-   plugin to directly copy or destroy a Blob.
- 
-   This is a pointer to host data which is opaque to the plugin. Plugins MUST
-   NOT interpret this data in any way, except via host-provided functions in
-   LV2_Blob_Support.
-*/
-typedef void* LV2_Blob;
-
-typedef void* LV2_Blob_Support_Data;
-
-typedef void (*LV2_Blob_Destroy)(LV2_Blob* blob);
-
-/**
-   The data field of the LV2_Feature for atom:BlobSupport.
- 
-   A host which supports blobs must pass an LV2_Feature to the plugin's
-   instantiate method with 'URI' = "http://lv2plug.in/ns/ext/atom#BlobSupport"
-   and 'data' pointing to an instance of this struct. All fields of this struct
-   MUST be set to non-NULL values by the host, except possibly 'data'.
-*/
-typedef struct {
-
-	/**
-	   Pointer to opaque host data.
-	 
-	   The plugin MUST pass this to any call to functions in this struct.
-	   Otherwise, the plugin MUST NOT interpret this value in any way.
-	*/
-	LV2_Blob_Support_Data data;
-
-	/**
-	   The size of a reference, in bytes.
-	 
-	   This value is provided by the host so plugins can allocate large enough
-	   chunks of memory to store references. Note a reference is an LV2_Atom
-	   with type atom:Reference, hence ref_size is a uint16, like
-	   LV2_Atom.size.
-	*/
-	uint16_t ref_size;
-	
-	/**
-	   Return the Blob referred to by @a ref.
-	 
-	   The returned value MUST NOT be used in any way other than by calling
-	   methods defined in LV2_Blob_Support (e.g. it MUST NOT be directly
-	   accessed, copied, or destroyed). The actual payload of the blob can
-	   be accessed with LV2_Blob_Support.blob_get.
-	*/
-	LV2_Blob (*ref_get)(LV2_Blob_Support_Data data,
-	                    LV2_Atom_Reference*   ref);
-
-	/**
-	   Copy a reference.
-	   This copies a reference but not the blob it refers to,
-	   i.e. after this call @a dst and @a src refer to the same LV2_Blob.
-	*/
-	void (*ref_copy)(LV2_Blob_Support_Data data,
-	                 LV2_Atom_Reference*   dst,
-	                 LV2_Atom_Reference*   src);
-
-	/**
-	   Reset (release) a reference.
-	   After this call, @a ref is invalid. Implementations must be sure to
-	   call this function when necessary, or memory leaks will result. The
-	   specific times this is necessary MUST be defined by any extensions that
-	   define a mechanism for transporting atoms. The standard semantics are:
-	   <ul><li>Whenever passed a Reference (e.g. via a Port) and run, the
-	   plugin owns that reference.</li>
-	   <li>The plugin owns any reference it creates (e.g. by using blob_new or
-	   ref_copy).</li>
-	   <li>For any reference it owns, the plugin MUST either:
-	   <ul><li>Copy the reference and store it (to be used in future runs and
-	   released later).</li>
-	   <li>Copy the reference to an output port exactly once.</li>
-	   <li>Release it with ref_reset.</li></ul></li>
-	   </ul>
-	*/
-	void (*ref_reset)(LV2_Blob_Support_Data data,
-	                  LV2_Atom_Reference*   ref);
-
-	/**
-	   Initialize a reference to point to a newly allocated Blob.
-
-	   @param data Must be the data member of this struct.
-	   @param ref Pointer to an area of memory at least as large as
-	   the ref_size field of this struct. On return, this will
-	   be the unique reference to the new blob, which is owned by the
-	   caller. Assumed to be uninitialised, i.e. the caller MUST NOT
-	   pass a valid reference since this could cause a memory leak.
-	   @param destroy Function to destroy this blob. This function
-	   MUST clean up any resources contained in the blob, but MUST NOT
-	   attempt to free the memory pointed to by its LV2_Blob* parameter
-	   (since this is allocated by the host).
-	   @param type ID of type of blob to allocate.
-	   @param size Size of blob to allocate in bytes.
-	*/
-	void (*blob_new)(LV2_Blob_Support_Data data,
-	                 LV2_Atom_Reference*   ref,
-	                 LV2_Blob_Destroy      destroy,
-	                 uint32_t              type,
-	                 size_t                size);
-	
-	/**
-	   Get blob's type as an ID.
-	 
-	   The return value may be any type URI, mapped to an integer with the
-	   URI Map extension with <code>context = NULL</code>.
-	*/
-	uint32_t (*blob_type)(LV2_Blob blob);
-
-	/**
-	   Get blob's body.
-	 
-	   Returns a pointer to the start of the blob data. The format of this
-	   data is defined by the return value of the type method. It MUST NOT
-	   be used in any way by code which does not understand that type.
-	*/
-	void* (*blob_data)(LV2_Blob blob);
-	
-} LV2_Blob_Support;
-
 #endif /* LV2_ATOM_H */
diff --git a/ext/atom.lv2/atom.ttl b/ext/atom.lv2/atom.ttl
index 25318d9..2043fbd 100644
--- a/ext/atom.lv2/atom.ttl
+++ b/ext/atom.lv2/atom.ttl
@@ -1,23 +1,17 @@
 # LV2 Atom Extension
-# Copyright (C) 2007-2011 David Robillard <d@drobilla.net>
-# 
-# Permission is hereby granted, free of charge, to any person obtaining a
-# copy of this software and associated documentation files (the "Software"),
-# to deal in the Software without restriction, including without limitation
-# the rights to use, copy, modify, merge, publish, distribute, sublicense,
-# and/or sell copies of the Software, and to permit persons to whom the
-# Software is furnished to do so, subject to the following conditions:
-# 
-# The above copyright notice and this permission notice shall be included
-# in all copies or substantial portions of the Software.
-# 
-# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
-# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
-# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
-# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
-# OTHER DEALINGS IN THE SOFTWARE.
+# Copyright 2007-2011 David Robillard <d@drobilla.net>
+#
+# Permission to use, copy, modify, and/or distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
 @prefix atom: <http://lv2plug.in/ns/ext/atom#> .
 @prefix doap: <http://usefulinc.com/ns/doap#> .
@@ -63,14 +57,6 @@ implementations to be polymorphic and extensible.</p>
 
 <p>Atoms (the start of the LV2_Atom header) MUST be 32-bit aligned.</p>
 
-<p>Optionally, the host MAY implement <a href="#blobSupport">blob support</a>.
-A <a href="#Blob">Blob</a> is a dynamically allocated chunk of memory
-that (unlike an Atom) is not necessarily POD.  Blobs are accessed via a
-<a href="#Reference">Reference</a>, which is a special case of Atom that
-always has <code>type = 0</code>, is not POD, and can only be copied using
-host provided functions.  This allows plugins and hosts to work with data
-of any type at all.</p>
-
 <p>Atoms can be communicated in many ways.  Since an Atom is the payload of an
 Event, an <a href="http://lv2plug.in/ns/ext/event#EventPort">EventPort</a>
 can be used for communicating Atoms in realtime with sub-sample time stamp
@@ -100,27 +86,14 @@ extension's <a href="urn:struct:LV2_URI_Map_Feature"
 >LV2_URI_Map_Feature</a>::uri_to_id with
 <code>map = "http://lv2plug.in/ns/ext/event"</code>.  If a plugin or host
 does not understand <code>type</code>, that atom SHOULD be gracefully ignored
-(or copied if it is not a <a href="#Reference">Reference</a>).</p>
-
-<p>All atoms are POD by definition except references, which have
-<code>type = 0</code>.  An Atom MUST NOT contain a Reference.  It is safe
-to copy any non-reference Atom with a simple <code>memcpy</code>, even if
-the implementation does not understand <code>type</code>.</p>
-""" .
-
-
-atom:Reference a rdfs:Class ;
-	rdfs:subClassOf atom:Atom ;
-	rdfs:label      "Reference" ;
-	lv2:documentation """
-<p>Reference to a <a href="#Blob">Blob</a>.  The actual contents of a Reference
-are opaque and host specific, and must not be copied, serialized, or otherwise
-interpreted by a plugin, except via functions provided by the host in
-<a href="urn:struct:LV2_Blob_Support">LV2_Blob_Support</a>.</p>
-
-<p>A Reference is a special case of Atom with <code>type = 0</code>.
-"Null" is the unique Atom with <code>type = 0</code> and
-<code>size = 0</code>.</p>
+(or copied if it does not have type 0).</p>
+
+<p>All atoms are POD by definition except references, which as a special case
+have <code>type = 0</code>.  An Atom MUST NOT contain a Reference.  It is safe
+to copy any non-reference Atom with a simple <code>memcpy</code>, even if the
+implementation does not understand <code>type</code>.  Though this extension reserves
+the type 0 for references, actual specification of how references are used is left
+to another extension.</p>
 """ .
 
 
@@ -362,22 +335,6 @@ and <code>data</code> pointing to a <a href="urn:struct:LV2_Blob_Support"
 """ .
 
 
-atom:Blob a rdfs:Class ;
-	rdfs:label      "Blob" ;
-	lv2:documentation """
-<p>Base class for all dynamically allocated blobs.  An <a
-href="urn:struct:LV2_Blob" >LV2_Blob</a> ia an opaque pointer to host
-data.  The type and data of a blob can be accessed via host-provided
-functions in <a href="urn:struct:LV2_Blob_Support">LV2_Blob_Support</a>.
-The type of a blob can be any URI that describes a data format.  Blobs are
-always allocated by the host, and unlike atoms are not necessarily POD.</p>
-
-<p>Blob data MUST NOT be used in any way by an implementation that does not
-understand that blob type (unlike Atoms, meaningful type-oblivious use
-of a Blob is impossible).</p>
-""" .
-
-
 atom:AtomPort a rdfs:Class ;
 	rdfs:subClassOf lv2:Port ;
 	rdfs:label      "Atom Port" ;
diff --git a/ext/reference.lv2/manifest.ttl b/ext/reference.lv2/manifest.ttl
new file mode 100644
index 0000000..e25c54d
--- /dev/null
+++ b/ext/reference.lv2/manifest.ttl
@@ -0,0 +1,9 @@
+@prefix lv2:  <http://lv2plug.in/ns/lv2core#> .
+@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
+
+<http://lv2plug.in/ns/ext/reference>
+	a lv2:Specification ;
+	lv2:minorVersion 0 ;
+	lv2:microVersion 1 ;
+	rdfs:seeAlso <reference.ttl> .
+
diff --git a/ext/reference.lv2/reference.h b/ext/reference.lv2/reference.h
new file mode 100644
index 0000000..043d3c2
--- /dev/null
+++ b/ext/reference.lv2/reference.h
@@ -0,0 +1,157 @@
+/*
+  Copyright 2008-2011 David Robillard <http://drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+/**
+   @file reference.h C header for the LV2 Reference extension
+   <http://lv2plug.in/ns/ext/reference>.
+*/
+
+#ifndef LV2_REFERENCE_H
+#define LV2_REFERENCE_H
+
+#define LV2_REFERENCE_URI              "http://lv2plug.in/ns/ext/reference"
+#define LV2_REFERENCE_BLOB_SUPPORT_URI LV2_REFERENCE_URI "#blobSupport"
+
+#include <stdint.h>
+#include <stddef.h>
+
+/**
+   Dynamically Allocated Data.
+ 
+   This is an opaque piece of data of any type, dynamically allocated in memory.
+   Unlike an "atom", a "blob" is not necessarily POD.  Non-POD data is referred
+   to by a "reference (a special case of atom with type 0).
+ 
+   This is a pointer to host data which is opaque to the plugin.  Plugins MUST
+   NOT interpret this data in any way, except via host-provided functions in
+   LV2_Blob_Support.
+*/
+typedef void* LV2_Blob;
+
+typedef void* LV2_Blob_Support_Data;
+
+typedef void (*LV2_Blob_Destroy)(LV2_Blob* blob);
+
+/**
+   The data field of the LV2_Feature for reference:blobSupport.
+ 
+   A host which supports blobs must pass an LV2_Feature to the plugin's
+   instantiate method with 'URI' = "http://lv2plug.in/ns/ext/reference#blobSupport"
+   and 'data' pointing to an instance of this struct. All fields of this struct
+   MUST be set to non-NULL values by the host, except possibly 'data'.
+*/
+typedef struct {
+
+	/**
+	   Pointer to opaque host data.
+	 
+	   The plugin MUST pass this to any call to functions in this struct.
+	   Otherwise, the plugin MUST NOT interpret this value in any way.
+	*/
+	LV2_Blob_Support_Data data;
+
+	/**
+	   The size of a reference, in bytes.
+	 
+	   This value is provided by the host so plugins can allocate large enough
+	   chunks of memory to store references. Note a reference is an LV2_Reference
+	   with type reference:Reference, hence ref_size is a uint16, like
+	   LV2_Reference.size.
+	*/
+	uint16_t ref_size;
+	
+	/**
+	   Return the Blob referred to by @a ref.
+	 
+	   The returned value MUST NOT be used in any way other than by calling
+	   methods defined in LV2_Blob_Support (e.g. it MUST NOT be directly
+	   accessed, copied, or destroyed). The actual payload of the blob can
+	   be accessed with LV2_Blob_Support.blob_get.
+	*/
+	LV2_Blob (*ref_get)(LV2_Blob_Support_Data    data,
+	                    LV2_Reference_Reference* ref);
+
+	/**
+	   Copy a reference.
+	   This copies a reference but not the blob it refers to,
+	   i.e. after this call @a dst and @a src refer to the same LV2_Blob.
+	*/
+	void (*ref_copy)(LV2_Blob_Support_Data    data,
+	                 LV2_Reference_Reference* dst,
+	                 LV2_Reference_Reference* src);
+
+	/**
+	   Reset (release) a reference.
+	   After this call, @a ref is invalid. Implementations must be sure to
+	   call this function when necessary, or memory leaks will result. The
+	   specific times this is necessary MUST be defined by any extensions that
+	   define a mechanism for transporting references. The standard semantics are:
+	   <ul><li>Whenever passed a Reference (e.g. via a Port) and run, the
+	   plugin owns that reference.</li>
+	   <li>The plugin owns any reference it creates (e.g. by using blob_new or
+	   ref_copy).</li>
+	   <li>For any reference it owns, the plugin MUST either:
+	   <ul><li>Copy the reference and store it (to be used in future runs and
+	   released later).</li>
+	   <li>Copy the reference to an output port exactly once.</li>
+	   <li>Release it with ref_reset.</li></ul></li>
+	   </ul>
+	*/
+	void (*ref_reset)(LV2_Blob_Support_Data    data,
+	                  LV2_Reference_Reference* ref);
+
+	/**
+	   Initialize a reference to point to a newly allocated Blob.
+
+	   @param data Must be the data member of this struct.
+	   @param ref Pointer to an area of memory at least as large as
+	   the ref_size field of this struct. On return, this will
+	   be the unique reference to the new blob, which is owned by the
+	   caller. Assumed to be uninitialised, i.e. the caller MUST NOT
+	   pass a valid reference since this could cause a memory leak.
+	   @param destroy Function to destroy this blob. This function
+	   MUST clean up any resources contained in the blob, but MUST NOT
+	   attempt to free the memory pointed to by its LV2_Blob* parameter
+	   (since this is allocated by the host).
+	   @param type ID of type of blob to allocate.
+	   @param size Size of blob to allocate in bytes.
+	*/
+	void (*blob_new)(LV2_Blob_Support_Data    data,
+	                 LV2_Reference_Reference* ref,
+	                 LV2_Blob_Destroy         destroy,
+	                 uint32_t                 type,
+	                 size_t                   size);
+	
+	/**
+	   Get blob's type as an ID.
+	 
+	   The return value may be any type URI, mapped to an integer with the
+	   URI Map extension with <code>context = NULL</code>.
+	*/
+	uint32_t (*blob_type)(LV2_Blob blob);
+
+	/**
+	   Get blob's body.
+	 
+	   Returns a pointer to the start of the blob data. The format of this
+	   data is defined by the return value of the type method. It MUST NOT
+	   be used in any way by code which does not understand that type.
+	*/
+	void* (*blob_data)(LV2_Blob blob);
+	
+} LV2_Blob_Support;
+
+#endif /* LV2_REFERENCE_H */
diff --git a/ext/reference.lv2/reference.ttl b/ext/reference.lv2/reference.ttl
new file mode 100644
index 0000000..8c8281f
--- /dev/null
+++ b/ext/reference.lv2/reference.ttl
@@ -0,0 +1,84 @@
+# LV2 Reference Extension
+# Copyright 2007-2011 David Robillard <d@drobilla.net>
+#
+# Permission to use, copy, modify, and/or distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+@prefix atom:      <http://lv2plug.in/ns/ext/atom#> .
+@prefix doap:      <http://usefulinc.com/ns/doap#> .
+@prefix foaf:      <http://xmlns.com/foaf/0.1/> .
+@prefix lv2:       <http://lv2plug.in/ns/lv2core#> .
+@prefix rdf:       <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
+@prefix rdfs:      <http://www.w3.org/2000/01/rdf-schema#> .
+@prefix reference: <http://lv2plug.in/ns/ext/reference#> .
+
+<http://lv2plug.in/ns/ext/reference>
+	a lv2:Specification ;
+	doap:name "LV2 Reference" ;
+    doap:release [
+        doap:revision "0.1" ;
+        doap:created "2011-07-22"
+    ] ;
+	doap:maintainer [
+		a foaf:Person ;
+		foaf:name	 "David Robillard" ;
+		foaf:homepage <http://drobilla.net/> ;
+		rdfs:seeAlso  <http://drobilla.net/drobilla.rdf>
+	] ;
+	lv2:documentation """
+<p>This extension defines a mechanism for working with generic/opaque
+dynamically allocated memory, called a <a href="#Blob">"Blob"</a>, which is
+(unlike an Atom) not necessarily POD.  Blobs are accessed via a <a
+href="#Reference">Reference</a>, which is a special case of Atom that always
+has <code>type = 0</code>, is not POD, and can only be copied using host
+provided functions.  This allows plugins and hosts to work with data of any
+type at all.</p>
+""" .
+
+reference:Reference a rdfs:Class ;
+	rdfs:subClassOf atom:Atom ;
+	rdfs:label      "Reference" ;
+	lv2:documentation """
+<p>Reference to a <a href="#Blob">Blob</a>.  The actual contents of a Reference
+are opaque and host specific, and must not be copied, serialized, or otherwise
+interpreted by a plugin, except via functions provided by the host in
+<a href="urn:struct:LV2_Blob_Support">LV2_Blob_Support</a>.</p>
+
+<p>A Reference is a special case of Atom with <code>type = 0</code>.
+"Null" is the unique Atom with <code>type = 0</code> and
+<code>size = 0</code>.</p>
+""" .
+
+reference:blobSupport a lv2:Feature ;
+	rdfs:label "Blob support" ;
+	lv2:documentation """
+Support for dynamically allocated blobs.  If a host supports this feature, it
+MUST pass a <a href="urn:struct:LV2_Feature">LV2_Feature</a> with
+<code>URI</code> http://lv2plug.in/ns/ext/atom#blobSupport
+and <code>data</code> pointing to a <a href="urn:struct:LV2_Blob_Support"
+>LV2_Blob_Support</a>.
+""" .
+
+reference:Blob a rdfs:Class ;
+	rdfs:label      "Blob" ;
+	lv2:documentation """
+<p>Base class for all dynamically allocated blobs.  An <a
+href="urn:struct:LV2_Blob" >LV2_Blob</a> ia an opaque pointer to host
+data.  The type and data of a blob can be accessed via host-provided
+functions in <a href="urn:struct:LV2_Blob_Support">LV2_Blob_Support</a>.
+The type of a blob can be any URI that describes a data format.  Blobs are
+always allocated by the host, and unlike atoms are not necessarily POD.</p>
+
+<p>Blob data MUST NOT be used in any way by an implementation that does not
+understand that blob type (unlike Atoms, meaningful type-oblivious use
+of a Blob is impossible).</p>
+""" .