diff --git a/doc/devel/uml/class128517.html b/doc/devel/uml/class128517.html
index 31e491fce..f82e4009d 100644
--- a/doc/devel/uml/class128517.html
+++ b/doc/devel/uml/class128517.html
@@ -20,8 +20,7 @@
 <p>Artifact : <a href="index.html#refartifact128261"><b>mobject</b></a>, Component(s) : <a href="index.html#refcomponent128133"><b>Session</b></a></p><div class="sub">
 <a name="refattribute128517"></a>
 <table><tr><td><div class="element">Attribut <b>length</b></div></td></tr></table>
-<p>Declaration :</p><ul><li>Uml : # length : <a href="class134917.html#refclass134917"><b>Time</b></a></li><li>C++ : protected: <a href="class134917.html#refclass134917"><b>Time</b></a> length</li></ul><p>TODO: how to represent time intervals?<br /></p><a name="refrelation129029"></a>
-<table><tr><td><div class="element">Relation <b>placement (&lt;association&gt;)</b></div></td></tr></table><p>Declaration :</p><ul><li>Uml : # placement : <a href="class128645.html#refclass128645"><b>Placement</b></a>, multiplicity : 1..*</li><li>C++ : protected: list&lt;<a href="class128645.html#refclass128645"><b>Placement</b></a> *&gt; placement</li></ul></div>
+<p>Declaration :</p><ul><li>Uml : # length : <a href="class134917.html#refclass134917"><b>Time</b></a></li><li>C++ : protected: <a href="class134917.html#refclass134917"><b>Time</b></a> length</li></ul><p>TODO: how to represent time intervals?<br /></p></div>
 <p>All public operations : <a href="class134021.html#refoperation129669"><b>apply</b></a> </p>
 </body>
 </html>
diff --git a/doc/devel/uml/class128645.html b/doc/devel/uml/class128645.html
index b87a32e2c..88a24bf13 100644
--- a/doc/devel/uml/class128645.html
+++ b/doc/devel/uml/class128645.html
@@ -18,9 +18,9 @@
 <a name="refclass128645"></a>
 <p>Declaration :</p><ul><li>C++ : class Placement </li><li>Java : public interface Placement </li></ul><p>Directly inherited by : <a href="class129541.html#refclass129541"><b>Allocation</b></a> <a href="class129797.html#refclass129797"><b>ExplicitPlacement</b></a> <a href="class129285.html#refclass129285"><b>FixedPlacement</b></a> <a href="class129413.html#refclass129413"><b>RelativePlacement</b></a> </p>
 <p>Artifact : <a href="index.html#refartifact129029"><b>placement</b></a></p><div class="sub">
-<a name="refrelation129157"></a>
-<table><tr><td><div class="element">Relation <b>subject (&lt;association&gt;)</b></div></td></tr></table><p>Declaration :</p><ul><li>Uml : # subject : <a href="class128517.html#refclass128517"><b>MObject</b></a>, multiplicity : 1</li><li>C++ : protected: <a href="class128517.html#refclass128517"><b>MObject</b></a>* subject</li></ul><a name="refoperation128005"></a>
-<table><tr><td><div class="element">Operation <b>resolve</b></div></td></tr></table><p>Declaration :</p><ul><li>Uml : + resolve() : ExplicitPlacement   [ProcessingLayer::MObject]&amp;</li><li>C++ : public: ExplicitPlacement   [ProcessingLayer::MObject]&amp; resolve () </li></ul><p>create an actual (explicit) placement while trying to satisfy the network of adjacent objects and placements.<br /></p></div>
+<a name="refoperation128005"></a>
+<table><tr><td><div class="element">Operation <b>resolve</b></div></td></tr></table><p>Declaration :</p><ul><li>Uml : + resolve() : ExplicitPlacement   [ProcessingLayer::MObject]&amp;</li><li>C++ : public: ExplicitPlacement   [ProcessingLayer::MObject]&amp; resolve () </li></ul><p>create an actual (explicit) placement while trying to satisfy the network of adjacent objects and placements.<br /></p><a name="refrelation144901"></a>
+<table><tr><td><div class="element">Relation <b>subject (&lt;unidirectional association&gt;)</b></div></td></tr></table><p>Declaration :</p><ul><li>Uml : # subject : <a href="class128517.html#refclass128517"><b>MObject</b></a>, multiplicity : 1</li><li>C++ : protected: <a href="class128517.html#refclass128517"><b>MObject</b></a>* subject</li></ul><p>Placement acts as smart pointer<br /></p></div>
 <p>All public operations : <a href="class128645.html#refoperation128005"><b>resolve</b></a> </p>
 </body>
 </html>
diff --git a/doc/devel/uml/fig128133.png b/doc/devel/uml/fig128133.png
index 70b2dd611..7a51ef88d 100644
Binary files a/doc/devel/uml/fig128133.png and b/doc/devel/uml/fig128133.png differ
diff --git a/doc/devel/uml/index.html b/doc/devel/uml/index.html
index 95d9a7166..dc0e8f165 100644
--- a/doc/devel/uml/index.html
+++ b/doc/devel/uml/index.html
@@ -112,7 +112,7 @@ Documentation</title>
 <a name="refartifact128005"></a>
 <table><tr><td><div class="element">Artifact <b>Cinelerra3</b></div></td></tr></table>
 <p>Depends on <a href="index.html#refpackage129413"><b>common</b></a></p><p>Depends on <a href="index.html#refpackage129797"><b>gui</b></a></p><p>Depends on <a href="index.html#refpackage129669"><b>proc</b></a></p><p>Depends on <a href="index.html#refpackage129541"><b>backend</b></a></p><p>the main executable to be built<br /></p>
-<p><i>executable</i> associated with : <a href="index.html#refartifact132229"><b>exitnode</b></a>, <a href="index.html#refartifact131717"><b>pathmanager</b></a>, <a href="index.html#refartifact128901"><b>track</b></a>, <a href="index.html#refartifact134533"><b>paramprovider</b></a>, <a href="index.html#refartifact132997"><b>mask</b></a>, <a href="index.html#refartifact128133"><b>main</b></a>, <a href="index.html#refartifact130693"><b>conmanager</b></a>, <a href="index.html#refartifact129413"><b>clip</b></a>, <a href="index.html#refartifact129669"><b>meta</b></a>, <a href="index.html#refartifact129797"><b>fixedplacement</b></a>, <a href="index.html#refartifact129925"><b>relativeplacement</b></a>, <a href="index.html#refartifact133509"><b>vrender</b></a>, <a href="index.html#refartifact128261"><b>mobject</b></a>, <a href="index.html#refartifact134277"><b>source</b></a>, <a href="index.html#refartifact133765"><b>frame</b></a>, <a href="index.html#refartifact129029"><b>placement</b></a>, <a href="index.html#refartifact128517"><b>sessionimpl</b></a>, <a href="index.html#refartifact130437"><b>builderfacade</b></a>, <a href="index.html#refartifact131589"><b>controllerfacade</b></a>, <a href="index.html#refartifact132101"><b>processor</b></a>, <a href="index.html#refartifact133125"><b>pluginadapter</b></a>, <a href="index.html#refartifact129541"><b>effect</b></a>, <a href="index.html#refartifact131205"><b>tool</b></a>, <a href="index.html#refartifact131333"><b>segmentationtool</b></a>, <a href="index.html#refartifact133893"><b>aframe</b></a>, <a href="index.html#refartifact130821"><b>assembler</b></a>, <a href="index.html#refartifact132485"><b>trafo</b></a>, <a href="index.html#refartifact129157"><b>explicitplacement</b></a>, <a href="index.html#refartifact130309"><b>auto</b></a>, <a href="index.html#refartifact133637"><b>glrender</b></a>, <a href="index.html#refartifact132613"><b>link</b></a>, <a href="index.html#refartifact134405"><b>parameter</b></a>, <a href="index.html#refartifact131973"><b>renderengine</b></a>, <a href="index.html#refartifact130053"><b>allocation</b></a>, <a href="index.html#refartifact134021"><b>vframe</b></a>, <a href="index.html#refartifact130565"><b>toolfactory</b></a>, <a href="index.html#refartifact133381"><b>arender</b></a>, <a href="index.html#refartifact131845"><b>renderstate</b></a>, <a href="index.html#refartifact130181"><b>label</b></a>, <a href="index.html#refartifact134149"><b>glbuf</b></a>, <a href="index.html#refartifact132357"><b>procnode</b></a>, <a href="index.html#refartifact130949"><b>stateproxy</b></a>, <a href="index.html#refartifact132741"><b>hub</b></a>, <a href="index.html#refartifact131077"><b>buildable</b></a>, <a href="index.html#refartifact129285"><b>abstractmo</b></a>, <a href="index.html#refartifact131461"><b>nodecreatertool</b></a>, <a href="index.html#refartifact132869"><b>projector</b></a>, <a href="index.html#refartifact134661"><b>interpolator</b></a>, <a href="index.html#refartifact128645"><b>edl</b></a>, <a href="index.html#refartifact128773"><b>fixture</b></a>, <a href="index.html#refartifact133253"><b>glpipe</b></a></p>
+<p><i>executable</i> associated with : <a href="index.html#refartifact128133"><b>main</b></a>, <a href="index.html#refartifact130693"><b>conmanager</b></a>, <a href="index.html#refartifact129413"><b>clip</b></a>, <a href="index.html#refartifact129669"><b>meta</b></a>, <a href="index.html#refartifact129797"><b>fixedplacement</b></a>, <a href="index.html#refartifact129925"><b>relativeplacement</b></a>, <a href="index.html#refartifact133509"><b>vrender</b></a>, <a href="index.html#refartifact128261"><b>mobject</b></a>, <a href="index.html#refartifact134277"><b>source</b></a>, <a href="index.html#refartifact133765"><b>frame</b></a>, <a href="index.html#refartifact129029"><b>placement</b></a>, <a href="index.html#refartifact128517"><b>sessionimpl</b></a>, <a href="index.html#refartifact130437"><b>builderfacade</b></a>, <a href="index.html#refartifact131589"><b>controllerfacade</b></a>, <a href="index.html#refartifact132101"><b>processor</b></a>, <a href="index.html#refartifact133125"><b>pluginadapter</b></a>, <a href="index.html#refartifact129541"><b>effect</b></a>, <a href="index.html#refartifact131205"><b>tool</b></a>, <a href="index.html#refartifact131333"><b>segmentationtool</b></a>, <a href="index.html#refartifact133893"><b>aframe</b></a>, <a href="index.html#refartifact130821"><b>assembler</b></a>, <a href="index.html#refartifact132485"><b>trafo</b></a>, <a href="index.html#refartifact129157"><b>explicitplacement</b></a>, <a href="index.html#refartifact130309"><b>auto</b></a>, <a href="index.html#refartifact133637"><b>glrender</b></a>, <a href="index.html#refartifact132613"><b>link</b></a>, <a href="index.html#refartifact134405"><b>parameter</b></a>, <a href="index.html#refartifact131973"><b>renderengine</b></a>, <a href="index.html#refartifact130053"><b>allocation</b></a>, <a href="index.html#refartifact134021"><b>vframe</b></a>, <a href="index.html#refartifact130565"><b>toolfactory</b></a>, <a href="index.html#refartifact133381"><b>arender</b></a>, <a href="index.html#refartifact131845"><b>renderstate</b></a>, <a href="index.html#refartifact130181"><b>label</b></a>, <a href="index.html#refartifact134149"><b>glbuf</b></a>, <a href="index.html#refartifact132357"><b>procnode</b></a>, <a href="index.html#refartifact130949"><b>stateproxy</b></a>, <a href="index.html#refartifact132741"><b>hub</b></a>, <a href="index.html#refartifact131077"><b>buildable</b></a>, <a href="index.html#refartifact129285"><b>abstractmo</b></a>, <a href="index.html#refartifact131461"><b>nodecreatertool</b></a>, <a href="index.html#refartifact132869"><b>projector</b></a>, <a href="index.html#refartifact134661"><b>interpolator</b></a>, <a href="index.html#refartifact128645"><b>edl</b></a>, <a href="index.html#refartifact128773"><b>fixture</b></a>, <a href="index.html#refartifact133253"><b>glpipe</b></a>, <a href="index.html#refartifact132229"><b>exitnode</b></a>, <a href="index.html#refartifact131717"><b>pathmanager</b></a>, <a href="index.html#refartifact128901"><b>track</b></a>, <a href="index.html#refartifact134533"><b>paramprovider</b></a>, <a href="index.html#refartifact132997"><b>mask</b></a></p>
 <a name="refartifact128133"></a>
 <table><tr><td><div class="element">Artifact <b>main</b></div></td></tr></table>
 <p>Artifact <i>source</i></p>
@@ -905,34 +905,25 @@ reuse exiting Engine</pre></li></ul><p>Selection :</p><ul></ul><p>Transformation
 <table><tr><td><div class="element">Class instance  <b>vid_A</div></td></tr></table><p>type :<a href="class128901.html#refclass128901"><b>Clip</b></a></p><p>attributes :<ul>
 <li><a href="class128517.html#refattribute128517"><b>length</b></a> = 5</li>
 <li><a href="class128901.html#refattribute128645"><b>start</b></a> = 100</li>
-</ul></p><p>relations :<ul>
-<li><a href="class128517.html#refrelation129029"><b>placement</b></a> = <a href="index.html#refclass instance130053"><b>class instance</b></a></li>
 </ul></p><a name="refclass instance130053"></a>
 <table><tr><td><div class="element">Class instance  <b></div></td></tr></table><p>type :<a href="class129413.html#refclass129413"><b>RelativePlacement</b></a></p><p>attributes :<ul>
 <li><a href="class129413.html#refattribute128133"><b>relType</b></a> = SAMETIME</li>
 </ul></p><p>relations :<ul>
 <li><a href="class129413.html#refrelation130565"><b>anchor</b></a> = <a href="index.html#refclass instance129669"><b>refPoint</b></a></li>
-<li><a href="class128645.html#refrelation129157"><b>subject</b></a> = <a href="index.html#refclass instance129925"><b>vid_A</b></a></li>
 </ul></p><a name="refclass instance130181"></a>
 <table><tr><td><div class="element">Class instance  <b></div></td></tr></table><p>type :<a href="class129029.html#refclass129029"><b>Effect</b></a></p><p>attributes :<ul>
 <li><a href="class128517.html#refattribute128517"><b>length</b></a> = 3</li>
 <li><a href="class129029.html#refattribute128901"><b>plugID</b></a> = "Hue"</li>
-</ul></p><p>relations :<ul>
-<li><a href="class128517.html#refrelation129029"><b>placement</b></a> = <a href="index.html#refclass instance130309"><b>class instance</b></a></li>
 </ul></p><a name="refclass instance130309"></a>
 <table><tr><td><div class="element">Class instance  <b></div></td></tr></table><p>type :<a href="class129413.html#refclass129413"><b>RelativePlacement</b></a></p><p>attributes :<ul>
 <li><a href="class129413.html#refattribute129029"><b>offset</b></a> = +3</li>
 <li><a href="class129413.html#refattribute128133"><b>relType</b></a> = ATTACH</li>
 </ul></p><p>relations :<ul>
 <li><a href="class129413.html#refrelation130565"><b>anchor</b></a> = <a href="index.html#refclass instance129925"><b>vid_A</b></a></li>
-<li><a href="class128645.html#refrelation129157"><b>subject</b></a> = <a href="index.html#refclass instance130437"><b>class instance</b></a></li>
-<li><a href="class128645.html#refrelation129157"><b>subject</b></a> = <a href="index.html#refclass instance130181"><b>class instance</b></a></li>
 </ul></p><a name="refclass instance130437"></a>
 <table><tr><td><div class="element">Class instance  <b></div></td></tr></table><p>type :<a href="class129029.html#refclass129029"><b>Effect</b></a></p><p>attributes :<ul>
 <li><a href="class128517.html#refattribute128517"><b>length</b></a> = 3</li>
 <li><a href="class129029.html#refattribute128901"><b>plugID</b></a> = "Hue"</li>
-</ul></p><p>relations :<ul>
-<li><a href="class128517.html#refrelation129029"><b>placement</b></a> = <a href="index.html#refclass instance130309"><b>class instance</b></a></li>
 </ul></p><a name="refclass instance130565"></a>
 <table><tr><td><div class="element">Class instance  <b></div></td></tr></table><p>type :<a href="class129797.html#refclass129797"><b>ExplicitPlacement</b></a></p><p>attributes :<ul>
 <li><a href="class129797.html#refattribute128261"><b>time</b></a> = 5</li>
diff --git a/doc/devel/uml/index_69.html b/doc/devel/uml/index_69.html
index 20380e20a..0c7bddcba 100644
--- a/doc/devel/uml/index_69.html
+++ b/doc/devel/uml/index_69.html
@@ -18,14 +18,14 @@
 <table>
 <tr bgcolor=#f0f0f0><td align=center><b>Name</b></td><td align=center><b>Kind</b></td><td align=center><b>Description</b></td></tr>
 <tr bgcolor=#f0f0f0><td><a href="index.html#refartifact128645" target = "projectFrame"><b>edl</b></a></td><td>artifact</td><td>the (high level) Edit Decision List within the current Session</td></tr>
-<tr bgcolor=#f0f0f0><td><a href="index.html#refcomponent128389" target = "projectFrame"><b>EDL</b></a></td><td>component</td><td></td></tr>
 <tr bgcolor=#f0f0f0><td><a href="class128133.html#refclass128133" target = "projectFrame"><b>EDL</b></a></td><td>class</td><td></td></tr>
+<tr bgcolor=#f0f0f0><td><a href="index.html#refcomponent128389" target = "projectFrame"><b>EDL</b></a></td><td>component</td><td></td></tr>
 <tr bgcolor=#f0f0f0><td><a href="index.html#refobject diagram128773" target = "projectFrame"><b>EDL Example1</b></a></td><td>object diagram</td><td>A simple example showing how the actual objects are placed in the Fixture (=definitive playlist). It shows a Video and Audio clip placed on two tracks</td></tr>
 <tr bgcolor=#f0f0f0><td><a href="index.html#refobject diagram128901" target = "projectFrame"><b>EDL Example2</b></a></td><td>object diagram</td><td>More complex example showing the Object graph in the EDL and how it is linked into the Fixture to yield the actual locations. In this example, an HUE Effect is applied on a part of the Clip</td></tr>
 <tr bgcolor=#f0f0f0><td><a href="index.html#refrelation128005" target = "projectFrame"><b>edls</b></a></td><td>relation</td><td></td></tr>
 <tr bgcolor=#f0f0f0><td><a href="class137733.html#refclass137733" target = "projectFrame"><b>Effect</b></a></td><td>class</td><td>Effect or media processing component</td></tr>
-<tr bgcolor=#f0f0f0><td><a href="index.html#refartifact129541" target = "projectFrame"><b>effect</b></a></td><td>artifact</td><td>EDL representation of a pluggable and automatable effect.</td></tr>
 <tr bgcolor=#f0f0f0><td><a href="index.html#refartifact137221" target = "projectFrame"><b>effect</b></a></td><td>artifact</td><td>Effect or media processing component</td></tr>
+<tr bgcolor=#f0f0f0><td><a href="index.html#refartifact129541" target = "projectFrame"><b>effect</b></a></td><td>artifact</td><td>EDL representation of a pluggable and automatable effect.</td></tr>
 <tr bgcolor=#f0f0f0><td><a href="class129029.html#refclass129029" target = "projectFrame"><b>Effect</b></a></td><td>class</td><td></td></tr>
 <tr bgcolor=#f0f0f0><td><a href="index.html#refrelation138885" target = "projectFrame"><b>elements</b></a></td><td>relation</td><td>relevant MObjects comprising this segment. TODO: actually necessary??</td></tr>
 <tr bgcolor=#f0f0f0><td><a href="index.html#refoperation132997" target = "projectFrame"><b>enable</b></a></td><td>operation</td><td>change the enabled status of this asset. Note the corresponding #isActive predicate may depend on the enablement status of parent assets as well</td></tr>
diff --git a/doc/devel/uml/index_80.html b/doc/devel/uml/index_80.html
index d7038cb97..20ee4971b 100644
--- a/doc/devel/uml/index_80.html
+++ b/doc/devel/uml/index_80.html
@@ -26,7 +26,6 @@
 <tr bgcolor=#f0f0f0><td><a href="class130437.html#refclass130437" target = "projectFrame"><b>PathManager</b></a></td><td>class</td><td>While building a render engine, this Strategy class decides on the actual render strategy in accordance to the current controller settings (system state)</td></tr>
 <tr bgcolor=#f0f0f0><td><a href="index.html#refartifact131717" target = "projectFrame"><b>pathmanager</b></a></td><td>artifact</td><td>Manager for deciding the actual render strategy</td></tr>
 <tr bgcolor=#f0f0f0><td><a href="index.html#refartifact129029" target = "projectFrame"><b>placement</b></a></td><td>artifact</td><td>Key Abstraction: a way to place and locate a Media Object</td></tr>
-<tr bgcolor=#f0f0f0><td><a href="index.html#refrelation129029" target = "projectFrame"><b>placement</b></a></td><td>relation</td><td></td></tr>
 <tr bgcolor=#f0f0f0><td><a href="class128645.html#refclass128645" target = "projectFrame"><b>Placement</b></a></td><td>class</td><td></td></tr>
 <tr bgcolor=#f0f0f0><td><a href="index.html#refoperation129413" target = "projectFrame"><b>play</b></a></td><td>operation</td><td>TODO: will probably be handled differently (see Cehteh)</td></tr>
 <tr bgcolor=#f0f0f0><td><a href="index.html#refnode128261" target = "projectFrame"><b>playlist</b></a></td><td>node</td><td></td></tr>
diff --git a/doc/devel/uml/index_83.html b/doc/devel/uml/index_83.html
index 847982657..5c1a18530 100644
--- a/doc/devel/uml/index_83.html
+++ b/doc/devel/uml/index_83.html
@@ -62,7 +62,7 @@
 <tr bgcolor=#f0f0f0><td><a href="class136965.html#refclass136965" target = "projectFrame"><b>Struct</b></a></td><td>class</td><td>key abstraction: structural asset</td></tr>
 <tr bgcolor=#f0f0f0><td><a href="index.html#refartifact136709" target = "projectFrame"><b>struct</b></a></td><td>artifact</td><td>key abstraction: structural asset</td></tr>
 <tr bgcolor=#f0f0f0><td><a href="index.html#refclass diagram131205" target = "projectFrame"><b>Struct-Asset Relations</b></a></td><td>class diagram</td><td></td></tr>
-<tr bgcolor=#f0f0f0><td><a href="index.html#refrelation129157" target = "projectFrame"><b>subject</b></a></td><td>relation</td><td></td></tr>
+<tr bgcolor=#f0f0f0><td><a href="index.html#refrelation144901" target = "projectFrame"><b>subject</b></a></td><td>relation</td><td>Placement acts as smart pointer</td></tr>
 <tr bgcolor=#f0f0f0><td><a href="index.html#refrelation144005" target = "projectFrame"><b>subPattern</b></a></td><td>relation</td><td></td></tr>
 </table>
 </body>
diff --git a/uml/cinelerra3/128133 b/uml/cinelerra3/128133
index 83eaacc4c..8438588b6 100644
--- a/uml/cinelerra3/128133
+++ b/uml/cinelerra3/128133
@@ -1,6 +1,6 @@
 format 40
 "Asset" // ProcessingLayer::Asset
-  revision 13
+  revision 14
   modified_by 5 "hiv"
   // class settings
   //class diagram settings
diff --git a/uml/cinelerra3/128133.diagram b/uml/cinelerra3/128133.diagram
index c0272f7ed..a1d67d92a 100644
--- a/uml/cinelerra3/128133.diagram
+++ b/uml/cinelerra3/128133.diagram
@@ -122,10 +122,6 @@ relationcanvas 129157 relation_ref 128389 // <directional aggregation by value>
   line 129285 z 1999 to ref 129029
   role_a_pos 338 687 3000 no_role_b
   multiplicity_a_pos 314 687 3000 no_multiplicity_b
-relationcanvas 129797 relation_ref 128645 // <association>
-  from ref 129413 z 1999 stereotype "<<list>>" xyz 471 143 3000 to ref 129669
-  role_a_pos 513 144 3000 role_b_pos 404 145 3000
-  multiplicity_a_pos 547 177 3000 multiplicity_b_pos 393 145 3000
 relationcanvas 130181 relation_ref 129029 // <directional aggregation by value>
   geometry HV
   from ref 128261 z 1999 stereotype "<<list>>" xyz 334 914 3000 to point 339 931
@@ -163,7 +159,7 @@ relationcanvas 132485 relation_ref 129797 // <generalisation>
 relationcanvas 132997 relation_ref 129925 // <unidirectional association>
   from ref 132869 z 1999 to point 529 240
   line 133893 z 1999 to ref 129413
-  role_a_pos 439 215 3000 no_role_b
+  role_a_pos 413 204 3000 no_role_b
   multiplicity_a_pos 401 197 3000 multiplicity_b_pos 515 251 3000
 relationcanvas 134533 relation_ref 130309 // <generalisation>
   from ref 134405 z 1999 to ref 131973
@@ -229,4 +225,8 @@ relationcanvas 139781 relation_ref 142853 // <unidirectional association>
   line 139909 z 1999 to ref 139653
   role_a_pos 152 426 3000 no_role_b
   multiplicity_a_pos 126 426 3000 no_multiplicity_b
+relationcanvas 140165 relation_ref 142981 // <unidirectional association>
+  from ref 129669 z 1999 to ref 129413
+  role_a_pos 413 146 3000 no_role_b
+  multiplicity_a_pos 403 146 3000 multiplicity_b_pos 547 148 3000
 end
diff --git a/uml/cinelerra3/128261 b/uml/cinelerra3/128261
index 48dbcaf73..60051e702 100644
--- a/uml/cinelerra3/128261
+++ b/uml/cinelerra3/128261
@@ -1,6 +1,6 @@
 format 40
 "MObject" // ProcessingLayer::MObject
-  revision 22
+  revision 23
   modified_by 5 "hiv"
   // class settings
   //class diagram settings
@@ -409,19 +409,6 @@ ${members}};
 	comment "TODO: how to represent time intervals?"
       end
 
-      classrelation 129029 // placement (<association>)
-	relation 128645 ----
-	  stereotype "list"
-	  a role_name "placement" multiplicity "1..*" protected
-	    cpp default "    ${comment}${static}${mutable}${volatile}${const}${stereotype}<${type} *> ${name}${value};
-"
-	    classrelation_ref 129029 // placement (<association>)
-	  b role_name "subject" multiplicity "1" protected
-	    cpp default "    ${comment}${static}${mutable}${volatile}${const}${type}* ${name}${value};
-"
-	    classrelation_ref 129157 // subject (<association>)
-      end
-
       classrelation 137093 // <generalisation>
 	relation 135557 ---|>
 	  a public
@@ -446,10 +433,6 @@ ${members}};
 "
       explicit_switch_type ""
       
-      classrelation 129157 // subject (<association>)
-	relation_ref 128645 // <association>
-      end
-
       operation 128005 "resolve"
 	public explicit_return_type "ExplicitPlacement   [ProcessingLayer::MObject]&"
 	nparams 0
@@ -465,6 +448,16 @@ ${class}::${name} ${(}${)}${const}${volatile} ${throw}${staticnl}
 	
 	comment "create an actual (explicit) placement while trying to satisfy the network of adjacent objects and placements."
       end
+
+      classrelation 144901 // subject (<unidirectional association>)
+	relation 142981 --->
+	  a role_name "subject" multiplicity "1" protected
+	    comment "Placement acts as smart pointer"
+	    cpp default "    ${comment}${static}${mutable}${volatile}${const}${type}* ${name}${value};
+"
+	    classrelation_ref 144901 // subject (<unidirectional association>)
+	  b multiplicity "1..*" parent class_ref 128517 // MObject
+      end
     end
 
     class 129797 "ExplicitPlacement"
diff --git a/uml/cinelerra3/5.session b/uml/cinelerra3/5.session
index 6811c0673..517123540 100644
--- a/uml/cinelerra3/5.session
+++ b/uml/cinelerra3/5.session
@@ -3,20 +3,20 @@ diagrams
   classdiagram_ref 130309 // Asset Kinds
     860 633 100 4 0 0
   active  classdiagram_ref 128133 // Session structure
-    860 633 100 4 120 0
+    860 633 100 4 47 0
   classdiagram_ref 130437 // Media-Asset Relations
     860 633 100 4 0 0
   classdiagram_ref 128389 // Render Entities
     688 506 100 4 120 0
 end
 show_stereotypes
-selected 
-  package_ref 129 // cinelerra3
+selected operation_ref 128005 // resolve
 open
   
-  package_ref 128005 // design
+package_ref 128005 // design
   classview_ref 128901 // Assets
-  class_ref 139781 // SessManager
+  class_ref 128645 // Placement
   classview_ref 129029 // Interface
+  usecaseview_ref 128133 // usage
 end
 end
diff --git a/uml/cinelerra3/cinelerra3.prj b/uml/cinelerra3/cinelerra3.prj
index 48d706651..4680e3711 100644
--- a/uml/cinelerra3/cinelerra3.prj
+++ b/uml/cinelerra3/cinelerra3.prj
@@ -1,6 +1,6 @@
 format 40
 "cinelerra3"
-  revision 31
+  revision 32
   modified_by 5 "hiv"
   cpp_root_dir "../../src/"
 
diff --git a/wiki/renderengine.html b/wiki/renderengine.html
index 294dda752..44e8ba1d4 100644
--- a/wiki/renderengine.html
+++ b/wiki/renderengine.html
@@ -514,7 +514,7 @@ ColorPalette
 
 SiteUrl</pre>
 </div>
-<div title="Asset" modifier="Ichthyostega" modified="200709040256" created="200708100337" tags="def classes" changecount="11">
+<div title="Asset" modifier="Ichthyostega" modified="200710092321" created="200708100337" tags="def classes" changecount="14">
 <pre>Asset management is a subsystem on its own. Assets are &quot;things&quot; that can be loaded into a session, like Media, Clips, Effects, Transitions. It is the &quot;bookkeeping view&quot;, while the EDL is the &quot;manipulation and process view&quot;. Some Assets can be //loaded// and a collection of Assets is saved with eatch Session. Besides, there is a collection of basic Assets allways available by default.
 
 The Assets are important reference points holding the information needed to access external resources. For example, an Clip asset can reference a Media asset, which in turn holds the external filename from which to get the media stream. For Effects, the situation is similar. Assets thus serve two quite distinct purposes. One is to load, list, group search and browse them, and to provide an entry point to create new or get at existing MObjects in the EDL, while the other purpose is to provide attribute and property informations to the inner parts of the engine, while at the same time isolating and decoupling them from environmental details. 
@@ -524,7 +524,7 @@ We can distinguish several different Kinds of Assets, each one with specific pro
 [img[Asset Classess|uml/fig130309.png]]
 
 !Media Asset
-Some piece of Media Data accessible at some external Location an able to be processed by Cinelerra. A Media File on Harddisk can be considered as the most basic form of Media Asset, with some important derived Flavours, like a Placeholder for a currently unavailable Source, or Media available in different Resolutions or Formats.
+Some piece of Media Data accessible at some external Location and able to be processed by Cinelerra. A Media File on Harddisk can be considered as the most basic form of Media Asset, with some important derived flavours, like a Placeholder for a currently unavailable Source, or Media available in different Resolutions or Formats.
 * __outward interface operations__ include querying properties, creating an Clip MObject, controlling processing policy (low res proxy placeholders, interlacing and other generic pre- and postprocessing)
 * __inward interface operations__ include querying filename, codec, offset and any other informations necessary for creating a source render node, getting additional processing policy decisions (handling of interlacing, aspect ratio).
 &amp;rarr; MediaAsset
@@ -548,9 +548,12 @@ Some additional, virtual facilities created in the course of the editing process
 &amp;rarr; MetaAsset {{red{to be defined}}}
 
 !!!!still to be worked out..
-is how to implement the relationship between [[MObject]]s and Assets. Do we use direct pointers, or do we prefer an ID + central registry approach? And how to handle the removal of an Asset 
+is how to implement the relationship between [[MObject]]s and Assets. Do we use direct pointers, or do we prefer an ID + central registry approach? And how to handle the removal of an Asset.
 &amp;rarr; see also [[analysis of mem management|ManagementAssetRelation]]
 &amp;rarr; see also [[Creating Objects|ObjectCreation]], especially [[Assets|AssetCreation]]
+
+  //9/07: currently implementing it as follows: use a refcounting-ptr from Clip-~MObject to asset::Media while maintaining a dependency network between Asset objects. We'll see if this approach is viable//
+
 </pre>
 </div>
 <div title="AssetCreation" modifier="Ichthyostega" created="200709040307" changecount="1">
@@ -770,7 +773,7 @@ Cinelerra uses this term in a related manner but with a somewhat shifted focus (
 In this usage, the EDL in most cases will be almost synonymous to the [[Session|SessionOverview]], just the latter emphasizes more the state aspect, as it can be thought as the current EDL contents contained in a file or data structure together with additional Option values and settings for the GUI. The Session is what you save and load, while the EDL rather denotes a structured collection of Objects placed in time.
 </pre>
 </div>
-<div title="EditingOperations" modifier="Ichthyostega" modified="200709251706" created="200709251610" tags="design decision" changecount="2">
+<div title="EditingOperations" modifier="Ichthyostega" modified="200710100119" created="200709251610" tags="design decision" changecount="4">
 <pre>These are the tools provided to any client of the Proc layer for handling and manipulating the entities in the EDL. When defining such operations, //the goal should be to arrive at some uniformity in the way things are done.// Ideally, when writing client code, one should be able to guess how to achieve some desired result.
 
 !guiding principle
@@ -779,7 +782,7 @@ The approach taken to define any operation is based primarily on the ''~OO-way o
 !main tasks
 * you ''create a clip'' either from a source media or from another clip (copy, maybe clone?). The new clip always reflects the full size (and other properties) of the source used for creating.
 * you can request a clip to ''resize'', which always relates to its current dimensions.
-* you can ''place or attach'' the clip to some point or other entity by creating a [[Placement]] from the clip.
+* you can ''place or attach'' the clip to some point or other entity by creating a [[Placement]] from the clip. (&amp;rarr; [[handling of Placements|PlacementHandling]])
 * you can ''adjust'' a placement relative to some other placement, meta object (i.e. selection), label or media, and this may cause the placement to resize or even delete the clip as necessary
 * you can perform ''adjustments'' on the whole EDL.
 All these operations propagate to directly dependant objects and may schedule global reconfigurations.
@@ -1356,14 +1359,14 @@ From experiences with other middle scale projects, I prefer having the test code
 
 {{red{how to create a test stub for this interface...?}}}</pre>
 </div>
-<div title="MObject" modifier="Ichthyostega" created="200706220312" tags="def classes" changecount="1">
-<pre>All sorts of &quot;things&quot; to be placed and manipulated by the user in the EDL. This interface abstracts the details and just provides
-* a duration
-* a [[Placement]]
+<div title="MObject" modifier="Ichthyostega" modified="200710092343" created="200706220312" tags="def classes" changecount="2">
+<pre>All sorts of &quot;things&quot; to be placed and manipulated by the user in the EDL. This interface abstracts the details and just supposes
+* the media object has a duration
+* it is allways //placed// in some manner, i.e. it is allways accessed via a [[Placement]]
 * {{red{and what else?}}}
 </pre>
 </div>
-<div title="MObjects" modifier="Ichthyostega" modified="200709030128" created="200706190636" tags="overview" changecount="8">
+<div title="MObjects" modifier="Ichthyostega" modified="200710100118" created="200706190636" tags="overview" changecount="9">
 <pre>The ~MObjects Subsystem contains everything related to the [[EDL]] and the various Media Objects placed within. It is complemented by the Asset Management (see &amp;rarr; [[Asset]]). Examples for [[MObjects|MObject]] being:
 * audio/video clips
 * effects and plugins
@@ -1372,6 +1375,10 @@ From experiences with other middle scale projects, I prefer having the test code
 * labels and other (maybe functional) markup
 
 This Design strives to achieve a StrongSeparation between the low-level Structures used to carry out the actual rendering and the high level Entities living in the EDL and being manipulated by the user. In this high level view, the Objects are grouped and located by [[Placements|Placement]], providing a flexible and open way to express different groupings, locations and ordering constraints between the Media Objects.
+&amp;rarr; EditingOperations
+&amp;rarr; PlacementHandling
+&amp;rarr; SessionOverview
+
 
 [img[Classess related to the EDL|uml/fig128133.png]]
 </pre>
@@ -1443,11 +1450,11 @@ For the case in question this seems to be the ''resource allocation is construct
 And, last but not least, doing all actual allocations is the job of the backend. Exceptions being long-lived objects, like the Session or the EDL, which are created once and don't bear the danger of causing memory pressure. Besides that, the ProcLayer code shouldn't issue &quot;new&quot; and &quot;delete&quot;, rather it should use some central [[Factories]] for all allocation and freeing, so we can redirect these calls down to the backend, which may use pooling or special placement allocators or the like. The rationale is, for modern hardware/architectures, care has to be taken with heap allocations, esp. with many small objects and irregular usage patterns.
 </pre>
 </div>
-<div title="MultichannelMedia" modifier="Ichthyostega" modified="200709220010" created="200709200255" tags="design" changecount="4">
+<div title="MultichannelMedia" modifier="Ichthyostega" modified="200710090015" created="200709200255" tags="design" changecount="5">
 <pre>Based on practical experiences, Ichthyo tends to consider Multichannel Media as the base case, while counting media files providing just one single media stream as exotic corner cases. This may seem counter intuitive at first sight; you should think of  it as an attempt to avoid right from start some of the common shortcomings found in many video editors, especially
 * having to deal with keeping a &quot;link&quot; between audio and video clips
-* silly limitations on the supported audio setups (e.g. mono, stereo and 5.1)
-* unnecessary complexity when dealing with more realistic setups, esp. when dealing with dialogue scenes
+* silly limitations on the supported audio setups (e.g. &quot;sound is mono, stereo or Dolby-5.1&quot;)
+* unnecessary complexity when dealing with more realistic setups, esp. when working on dialogue scenes
 * inability to edit stereoscopic (3D) video in a natural fashion
 
 !Compound Media
@@ -1456,22 +1463,21 @@ Basically, each [[media asset|MediaAsset]] is considered to be a compound of sev
 So, when creating a clip out of such a compound media asset, the clip has to be a compound of elementary clips mirroring the given media asset's structure. Besides, it should be possible to //detach// and //attach// elementary clips from a compound clip. On the other hand, the [[Fixture]] created from the current state of the [[EDL]] is explicit to a great extent. So, in the Fixture we deal only with elementary clips placed to absolute positions, and thus the builder will see only simple non-compound clips and translate them into the corresponding source reading nodes.
 
 !Handling
-* from a Media asset, we can get a [[Processing Pattern|ProcPatt]] describing how to build a render pipeline for this media
+* from a Media asset, we can get a [[Processing Pattern (ProcPatt)|ProcPatt]] describing how to build a render pipeline for this media
 * we can create a Clip (MObject) from each Media, which will be linked back to the media asset internally.
 * moreover, creating a Clip will create and register a Clip asset as well, and this Clip asset will be tied to the original Clip and will show up in some special Category
 * media can be compound and the created Clips will mirror this compound structure
 * we distinguish elementay (non-compound) Clips from compound clips by concrete subtype. The builder can only handle elementary clips, because he needs to build a separate pipeline for every output channel. So the work of splitting common effect stacks for clips with several channels needs to be done when calculating the Fixture for the current EDL. The Builder expects to be able to build the render nodes corresponding to each entity found in the Fixture one by one.
 * the Builder gets at the ProcPatt (descriptor) of the underlying media for each clip and uses this description as a template to build the render pipeline. That is, the ProcPatt specifies the codec asset and maybe some additional effect assets (deinterlace, scale) necessary for feeding media data corresponding to this clip/media into the render nodes network.</pre>
 </div>
-<div title="ObjectCreation" modifier="Ichthyostega" modified="200709040257" created="200709030139" tags="impl design" changecount="10">
-<pre>We have to consider carefully how to handle the Creation of new class instances. Because, when done naively, it can defeat all efforts of separating subsystems, or &amp;mdash; the other extreme &amp;mdash; lead to a //switch-on-typeID//  programming style. We strive at a solution somewhere in the middle by utilizing __Abstract Factories__ on Interface or key abstraction classes, but providing specialized overloads for the different use cases. So in each use case we have to decide if we want to create a representant of some general concept (Interface), or if we have a direct colaboration and thus need the Factory to provide
-a more specific sub-Interface or even a concrete type.
+<div title="ObjectCreation" modifier="Ichthyostega" modified="200710090219" created="200709030139" tags="impl design" changecount="15">
+<pre>We have to consider carefully how to handle the Creation of new class instances. Because, when done naively, it can defeat all efforts of separating subsystems, or &amp;mdash; the other extreme &amp;mdash; lead to a //switch-on-typeID//  programming style. We strive at a solution somewhere in the middle by utilizing __Abstract Factories__ on Interface or key abstraction classes, but providing specialized overloads for the different use cases. So in each use case we have to decide if we want to create a instance of some general concept (Interface), or if we have a direct collaboration and thus need the Factory to provide a more specific sub-Interface or even a concrete type.
 
 !Object creation use cases
 !![[Assets|Asset]]
 |!Action|&gt;|!creates |
 |loading a media file|asset::Media, asset::Codec| |
-|viewing media|asset::Clip| for the whole Media, if not already existant|
+|viewing media|asset::Clip| for the whole Media, if not already existent|
 |mark selection as clip|asset::Clip| doesn't add to EDL|
 |loading Plugin|asset::Effect| usually at program startup|
 |create Session|asset::Track, asset::OutPort| |
@@ -1482,7 +1488,12 @@ a more specific sub-Interface or even a concrete type.
 |add Clip|session::Clip, FixedPlacement| |
 |attach Effect|session::Effect, RelativePlacement| |
 |start using Automation|session::Auto, asset::Dataset, RelativePlacement| |
-</pre>
+
+!Invariants
+when creating Objects, certain invariants have to be maintained. Because creating an Object can be considered an atomic operation and must not leave any related objects in an inconsistent state. Each of our interfaces implies some invariants:
+* every Placement has a Subject it places
+* MObjects are always created to be placed in some way or the other
+* [[Assets|Asset]] manage a dependency graph. Creating a derived Object (e.g. a Clip from a Media) implies a new dependency. (&amp;rarr; [[memory management|ManagementAssetRelation]] relies on this)</pre>
 </div>
 <div title="OpenGL" modifier="Ichthyostega" modified="200706220359" created="200706220345" tags="def discuss" changecount="3">
 <pre>Cinelerra2 introduced OpenGL support for rendering previews. I must admit, I am very unhappy with this, because
@@ -2063,8 +2074,19 @@ DAMAGE.
 &lt;html&gt;&lt;sub&gt;&lt;a href=&quot;javascript:;&quot; onclick=&quot;scrollAnchorVisible('Top',null, event)&quot;&gt;[Top]&lt;/sub&gt;&lt;/a&gt;&lt;/html&gt;
 ***/</pre>
 </div>
-<div title="Placement" modifier="MichaelPloujnikov" modified="200706271459" created="200706220306" tags="def" changecount="3">
+<div title="Placement" modifier="Ichthyostega" modified="200710100120" created="200706220306" tags="def" changecount="6">
 <pre>A Placement represents a //relation:// it is always linked to a //Subject// (this being a [[Media Object|MObject]]) and has the meaning to //place// this Subject in some manner, either relatively to other Media Objects, or by some Constraint or simply absolute at (time,track). The latter case is especially important and represented by a special [[Sub-Interface|ExplicitPlacement]]
+
+The fact of being placed in the [[Session|SessionOverview]]/[[EDL]]is constitutive for all sorts of [[MObject]]s, without Placement they make no sense. Thus &amp;mdash; technically &amp;mdash; Placements act as ''smart pointers''. Of course, there are several kinds of Placements and they are templated on the type of MObject they are refering to. Placements can be //aggregated// to increasingly constrain the resulting &quot;location&quot; of the refered ~MObject. See &amp;rarr; [[handling of Placements|PlacementHandling]] for more details</pre>
+</div>
+<div title="PlacementHandling" modifier="Ichthyostega" modified="200710100148" created="200710100124" tags="design" changecount="3">
+<pre>[[Placement]]s are at the very core of all [[editing operations|EditingOperations]], because they act as handles (smart pointers) to access the [[media objects|MObject]] to be manipulated. Moreover, Placements are the actual content of the EDL(s) and Fixture and thus are small objects with //value semantics//. Many editing tasks include finding some Placement in the EDL or directly take a ref to some Placement. By acting on the Placement object, we can in some cases change parameters of the way the media object is placed (e.g. adjust an offset), while by dereferencing the Placement object, we access the &quot;real&quot; media object (e.g. for trimming its length).
+
+Placements are ''templated'' on the type of the actual ~MObject they refer to, thus defining the interface/methods usable on this object. Each Placement has a ''kind'', which determines its actual placing and locating behaviour, but besides that, we don't stress the identity of a placement object (~MObjects on the other hand //do have// a distinguishable identity): initially, you create a Placement of some specific kind (fixed, relative,...), but later on, you treat the placement polymorphically and don't care about its kind. The sole purpose of the placement's kind is to select some virtual function implementing the desired behaviour.
+
+There is no limitation to one single Placement per ~MObject, indeed we can ''aggregate'' several Placements, resulting in their properties and constraints being combined to yield the actual position of the ~MObject refered by those Placements. 
+
+* {{red{to be worked out...}}} how to implement this, esp. the aggregation. Use a special &quot;placement aggregation&quot; subtype, or rather chain aggregated placements directly in the way a decorator works? And how to handle the case of a //over constrained// Placement?
 </pre>
 </div>
 <div title="Playlist" modifier="Ichthyostega" modified="200706250727" created="200706220456" tags="def" changecount="3">