diff --git a/C4.puml b/C4.puml
index 6ec4334c..ec5a0a86 100644
--- a/C4.puml
+++ b/C4.puml
@@ -1293,6 +1293,57 @@ rectangle "$getBoundary($label, $type)" $toStereos("boundary", $boundaryTags) as
 ' Boundary Styling
 UpdateBoundaryStyle("", $bgColor=$BOUNDARY_BG_COLOR, $fontColor=$BOUNDARY_COLOR, $borderColor=$BOUNDARY_COLOR)
 
+' Index
+' ##################################
+
+' Dynamic/Sequence diagram supports (automatically) numbered interactions:
+'     preferred function calls
+'     (Uppercase) LastIndex(): return the last used index (function which can be used as argument)
+'     (Uppercase) Index($offset=1): returns current index and calculates next index (function which can be used as argument)
+'     (Uppercase) SetIndex($new_index): returns new set index and calculates next index (function which can be used as argument)
+
+'     old procedures calls
+'     (lowercase) increment($offset=1): increase current index (procedure which has no direct output)
+'     (lowercase) setIndex($new_index): set the new index (procedure which has no direct output)
+
+!$lastIndex = 0
+!$index = 1
+
+!procedure increment($offset=1)
+  !$lastIndex = $index
+  !$index = $index + $offset
+!endprocedure
+
+!procedure setIndex($new_index)
+  !$lastIndex = $index
+  !$index = $new_index
+!endprocedure
+
+!function Index($offset=1)
+  !$lastIndex = $index
+  !$index = $lastIndex + $offset
+  !return $lastIndex
+!endfunction
+
+!function LastIndex()
+  !return $lastIndex
+!endfunction
+
+!function SetIndex($new_index, $offset=1)
+  !$lastIndex = $new_index
+  !$index = $new_index + $offset
+  !return $lastIndex
+!endfunction
+
+!unquoted function $getPrefix($index)
+  !if ($index == "")
+    !$pre = Index() + ": "
+  !else
+    !$pre = $index + ": "
+  !endif
+  !return $pre
+!endfunction
+
 ' Relationship
 ' ##################################
 
diff --git a/C4_Dynamic.puml b/C4_Dynamic.puml
index 8633ec48..fa408ba8 100644
--- a/C4_Dynamic.puml
+++ b/C4_Dynamic.puml
@@ -20,38 +20,6 @@
 '     (Uppercase) Index($offset=1): returns current index and calculates next index (function which can be used as argument)
 '     (Uppercase) SetIndex($new_index): returns new set index and calculates next index (function which can be used as argument)
 
-' Index
-' ##################################
-
-!$lastIndex = 0
-!$index = 1
-
-!procedure increment($offset=1)
-  !$lastIndex = $index
-  !$index = $index + $offset
-!endprocedure
-
-!procedure setIndex($new_index)
-  !$lastIndex = $index
-  !$index = $new_index
-!endprocedure
-
-!function Index($offset=1)
-  !$lastIndex = $index
-  !$index = $lastIndex + $offset
-  !return $lastIndex
-!endfunction
-
-!function LastIndex()
-  !return $lastIndex
-!endfunction
-
-!function SetIndex($new_index, $offset=1)
-  !$lastIndex = $new_index
-  !$index = $new_index + $offset
-  !return $lastIndex
-!endfunction
-
 ' Relationship override
 ' ##################################
 
@@ -65,39 +33,47 @@ $getRel($direction, $alias1, $alias2, $e_index + ": " + $label, "", "", "", "",
 $getRel($direction, $alias1, $alias2, $e_index + ": " + $label, $techn, "", "", "", "")
 !endprocedure
 
-!unquoted procedure Rel($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
-$getRel("-->>", $from, $to, Index() + ": " + $label, $techn, $descr, $sprite, $tags, $link)
+' all RelIndex... calls are outdated, Rel(..., $index=...) calls should be used !!!!
+
+!unquoted procedure Rel($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="")
+!$pre = $getPrefix($index)
+$getRel("-->>", $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
 !unquoted procedure RelIndex($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
 $getRel("-->>", $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
 
-!unquoted procedure Rel_Back($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
-$getRel("<<--", $from, $to, Index() + ": " + $label, $techn, $descr, $sprite, $tags, $link)
+!unquoted procedure Rel_Back($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="")
+!$pre = $getPrefix($index)
+$getRel("<<--", $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
 !unquoted procedure RelIndex_Back($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
 $getRel("<<--", $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
 
-!unquoted procedure Rel_Neighbor($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
-$getRel("->>", $from, $to, Index() + ": " + $label, $techn, $descr, $sprite, $tags, $link)
+!unquoted procedure Rel_Neighbor($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="")
+!$pre = $getPrefix($index)
+$getRel("->>", $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
 !unquoted procedure RelIndex_Neighbor($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
 $getRel("->>", $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
 
-!unquoted procedure Rel_Back_Neighbor($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
-$getRel("<<-", $from, $to, Index() + ": " + $label, $techn, $descr, $sprite, $tags, $link)
+!unquoted procedure Rel_Back_Neighbor($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="")
+!$pre = $getPrefix($index)
+$getRel("<<-", $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
 !unquoted procedure RelIndex_Back_Neighbor($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
 $getRel("<<-", $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
 
-!unquoted procedure Rel_D($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
-$getRel($down("-","->>"), $from, $to, Index() + ": " + $label, $techn, $descr, $sprite, $tags, $link)
+!unquoted procedure Rel_D($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="")
+!$pre = $getPrefix($index)
+$getRel($down("-","->>"), $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
-!unquoted procedure Rel_Down($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
-$getRel($down("-","->>"), $from, $to, Index() + ": " + $label, $techn, $descr, $sprite, $tags, $link)
+!unquoted procedure Rel_Down($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="")
+!$pre = $getPrefix($index)
+$getRel($down("-","->>"), $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
 !unquoted procedure RelIndex_D($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
 $getRel($down("-","->>"), $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
@@ -106,11 +82,13 @@ $getRel($down("-","->>"), $from, $to, $e_index + ": " + $label, $techn, $descr,
 $getRel($down("-","->>"), $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
 
-!unquoted procedure Rel_U($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
-$getRel($up("-","->>"), $from, $to, Index() + ": " + $label, $techn, $descr, $sprite, $tags, $link)
+!unquoted procedure Rel_U($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="")
+!$pre = $getPrefix($index)
+$getRel($up("-","->>"), $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
-!unquoted procedure Rel_Up($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
-$getRel($up("-","->>"), $from, $to, Index() + ": " + $label, $techn, $descr, $sprite, $tags, $link)
+!unquoted procedure Rel_Up($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="")
+!$pre = $getPrefix($index)
+$getRel($up("-","->>"), $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
 !unquoted procedure RelIndex_U($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
 $getRel($up("-","->>"), $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
@@ -119,11 +97,13 @@ $getRel($up("-","->>"), $from, $to, $e_index + ": " + $label, $techn, $descr, $s
 $getRel($up("-","->>"), $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
 
-!unquoted procedure Rel_L($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
-$getRel($left("-","->>"), $from, $to, Index() + ": " + $label, $techn, $descr, $sprite, $tags, $link)
+!unquoted procedure Rel_L($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="")
+!$pre = $getPrefix($index)
+$getRel($left("-","->>"), $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
 !unquoted procedure Rel_Left($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
-$getRel($left("-","->>"), $from, $to, Index() + ": " + $label, $techn, $descr, $sprite, $tags, $link)
+!$pre = $getPrefix($index)
+$getRel($left("-","->>"), $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link, $index="")
 !endprocedure
 !unquoted procedure RelIndex_L($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
 $getRel($left("-","->>"), $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
@@ -132,11 +112,13 @@ $getRel($left("-","->>"), $from, $to, $e_index + ": " + $label, $techn, $descr,
 $getRel($left("-","->>"), $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
 
-!unquoted procedure Rel_R($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
-$getRel($right("-","->>"), $from, $to, Index() + ": " + $label, $techn, $descr, $sprite, $tags, $link)
+!unquoted procedure Rel_R($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="")
+!$pre = $getPrefix($index)
+$getRel($right("-","->>"), $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
-!unquoted procedure Rel_Right($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
-$getRel($right("-","->>"), $from, $to, Index() + ": " + $label, $techn, $descr, $sprite, $tags, $link)
+!unquoted procedure Rel_Right($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="")
+!$pre = $getPrefix($index)
+$getRel($right("-","->>"), $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
 !unquoted procedure RelIndex_R($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
 $getRel($right("-","->>"), $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
diff --git a/C4_Sequence.puml b/C4_Sequence.puml
index 16701bef..5938c813 100644
--- a/C4_Sequence.puml
+++ b/C4_Sequence.puml
@@ -61,6 +61,16 @@ UpdateBoundaryStyle("container", $bgColor=$CONTAINER_BOUNDARY_BG_COLOR, $fontCol
 !endif
 !endprocedure
 
+!global $show_index = %false()
+' All relation specific (default) ordinary index numbers can be shown with this call
+!unquoted procedure SHOW_INDEX($show="true")
+!if ($show == "true")
+  !global $show_index = %true()
+!else
+  !global $show_index = %false()
+!endif
+!endprocedure
+
 ' ======= if no theme is defined hide foot box and activate C4_blue styles
 !if (%variable_exists("$THEME"))
 !else
@@ -365,55 +375,20 @@ end box
   Boundary($alias, $label, "", $allTags, $link)
 !endprocedure
 
-
-' Index
-' ##################################
-
-!$lastIndex = 0
-!$index = 1
-
-!procedure increment($offset=1)
-  !$lastIndex = $index
-  !$index = $index + $offset
-!endprocedure
-
-!procedure setIndex($new_index)
-  !$lastIndex = $index
-  !$index = $new_index
-!endprocedure
-
-!function Index($offset=1)
-  !$lastIndex = $index
-  !$index = $lastIndex + $offset
-  !return $lastIndex
-!endfunction
-
-!function LastIndex()
-  !return $lastIndex
-!endfunction
-
-!function SetIndex($new_index, $offset=1)
-  !$lastIndex = $new_index
-  !$index = $new_index + $offset
-  !return $lastIndex
-!endfunction
-
 ' Relationship (redefinition)
 ' ##################################
 
-!unquoted procedure Rel_($e_index, $alias1, $alias2, $label, $direction)
-$getRel($direction, $alias1, $alias2, $e_index + ": " + $label, "", "", "", "", "")
-!endprocedure
-!unquoted procedure Rel_($e_index, $alias1, $alias2, $label, $techn, $direction)
-$getRel($direction, $alias1, $alias2, $e_index + ": " + $label, $techn, "", "", "", "")
-!endprocedure
+' only Rel is supported in sequence diagram
 
-!unquoted procedure Rel($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
-$getRel("->", $from, $to, Index() + ": " + $label, $techn, $descr, $sprite, $tags, $link)
-!endprocedure
-!unquoted procedure RelIndex($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
-$getRel("->", $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
-!endprocedure
-!unquoted procedure RelSpecialIndex($rel, $e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
-$getRel($rel, $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
+' don't add empty lines in procedure otherwise & calls are not working anymore '& a -> b: call' are not working anymore
+!unquoted procedure Rel($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="", $rel="")
+  !if ($show_index == %true())
+    !$pre = $getPrefix($index)
+  !else
+    !$pre = ""
+  !endif
+  !if ($rel == "")
+    !$rel = "->"
+  !endif
+$getRel($rel, $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
diff --git a/LayoutOptions.md b/LayoutOptions.md
index 730b8875..f1df309a 100644
--- a/LayoutOptions.md
+++ b/LayoutOptions.md
@@ -18,6 +18,10 @@ C4-PlantUML comes with some layout options.
     - [Using SHOW_PERSON_SPRITE(sprite)](#using-show_person_spritesprite)
     - [Using SHOW_PERSON_PORTRAIT()](#using-show_person_portrait)
     - [Using SHOW_PERSON_OUTLINE()](#using-show_person_outline)
+  - [(C4 styled) Sequence diagram specific layout options](#c4-styled-sequence-diagram-specific-layout-options)
+    - [SHOW_ELEMENT_DESCRIPTIONS(?show)](#show_element_descriptionsshow)
+    - [SHOW_FOOT_BOXES(?show)](#show_foot_boxesshow)
+    - [SHOW_INDEX(?show)](#show_indexshow)
 - [📄 Themes](Themes.md#themes)
 - samples
   - [📄 C4 Model Diagrams](samples/C4CoreDiagrams.md#c4-model-diagrams)
@@ -557,3 +561,78 @@ Rel(web_app, twitter, "Gets tweets from", "HTTPS")
 ```
 
 ![SHOW_PERSON_OUTLINE() Sample](https://www.plantuml.com/plantuml/png/RL5BQzj04BxhLqpTWcLm919wAXJY6jCK4bj4SdCK8sbYB-nZsHqXJEb_xopAeuVeeDNEV8_vHhUHCV1eDDHtXwUssZtMXtrxE3Rtl_QxV0Kr6gyf-wHihyU1uCpiuxUo33WL9yNdiHiZXTvP9ij5xqpfDTeaU1LvqAehjr-lgbGwFjoN1YDJa5Ax5GOgIw7mWiso3zsphA8GdSrnCCgkOR59fueSa5rOhBBw8dgc_U56Es2uvFtr6fRpoCiL_Cb0dZUdVAAkHUz5vuaws7YlLO-id5r8QVjv3PkwAlQxHYY1uAQuXeVVszJRQEsc22bf17OWCJqAn8oQbNX1CocMOC3Aa1QlABFzVPakvxafEYymQMPBKC-0u2db0nMJPYVC0GHpbaxqGJ41dycc5mJg6Ur9p3HUtCY9CqR1uqdIlIvgrXEh-JwBpL8IvClyzNqnmsxI88-aNzVxlfzZb0XotZLDLGigWTwwxtb-4aUvKZgUWpF_Ksx93kdF_WC0 "SHOW_PERSON_OUTLINE()")
+
+## (C4 styled) Sequence diagram specific layout options
+
+- **SHOW_ELEMENT_DESCRIPTIONS(?show)**: show or hide (hidden is default) all element/participant related descriptions
+- **SHOW_FOOT_BOXES(?show)**: show or hide (hidden is default) all element/participant related foot boxes
+- **SHOW_INDEX(?show)**: show or hide (hidden is default) the relationship (call) related index (sequence number)
+
+show is defined with `$show=true` and hide is defined with `$show=false`
+
+### SHOW_ELEMENT_DESCRIPTIONS(?show)
+
+```plantuml
+@startuml
+!include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Sequence.puml
+
+SHOW_ELEMENT_DESCRIPTIONS()
+
+Person(admin, "Administrator", "People that administrates the products")
+System_Boundary(c1, 'Sample')
+    Container(web_app, "Web Application", "C#, ASP.NET Core 2.1 MVC", "Allows users to compare multiple Twitter timelines")
+' in a sequence diagram Boundary_End() has to be used instead of  { }
+Boundary_End()
+System(twitter, "Twitter")
+
+Rel(admin, web_app, "Uses", "HTTPS")
+Rel(web_app, twitter, "Gets tweets from", "HTTPS")
+@enduml
+```
+
+![SHOW_ELEMENT_DESCRIPTIONS() Sample](https://www.plantuml.com/plantuml/png/LL1DRzD04BtxLmpX44TARHLnujHWB5gfIQtQfKThx9qsA-t7iZihgqByTtOX8U3Boc_Unvkv2OoUerR5Esbc5GN1aTc5JtNjSQbU9H_Z50FvsHecmzLiTUqKcgov2YoKdEhcurMNeQVzVQqnCFa4ZJrzZsHcgbosB_hRX-UnlM_txM4OlxHzytZN3NSFXxxS54L7FbXJej3IR66rowyCx96jNoMW8-iK0H-H0Iz32WaYSDwAE7DOROh-BSNhyREDHg1_A-VhBQnxr4cztXIGliOQHcd8bmjD8pgNx9zfWfrpIix8qfgSsBpVmgxlgaCx98ad-51Tm_vRasSxfUmI89yb05kOhNQOA3egbhddi4Xcyi1IaqfPkTaQf064SBeA28cl7ZMSguwj4UK6ZlZRSg9iBv8cCA40-mBm0tuM_xDFwvRy9ozLEoMdlEAHrFcWbqsV0eMymkqmT7rYPTBVwSNcAt58lvIV5s_rlv8RCY9gzGi0 "SHOW_ELEMENT_DESCRIPTIONS() Sample")
+
+### SHOW_FOOT_BOXES(?show)
+
+```plantuml
+@startuml
+!include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Sequence.puml
+
+SHOW_FOOT_BOXES()
+
+Person(admin, "Administrator")
+System_Boundary(c1, 'Sample')
+    Container(web_app, "Web Application", "C#, ASP.NET Core 2.1 MVC", "Allows users to compare multiple Twitter timelines")
+' in a sequence diagram Boundary_End() has to be used instead of  { }
+Boundary_End()
+System(twitter, "Twitter")
+
+Rel(admin, web_app, "Uses", "HTTPS")
+Rel(web_app, twitter, "Gets tweets from", "HTTPS")
+@enduml
+```
+
+![SHOW_FOOT_BOXES() Sample](https://www.plantuml.com/plantuml/png/LL1DRzD04BtlhnZ28OwKsYhYnAbf5EY1aWYxb9irzawRbVPZsPrLL27-ExEY8U3Bo3FluxszoOo9YxFgZV6pBPhWo1ppXwvBU6gV3H_BL3AbENWcp-qSN1Sj-igvogojcRhj-wj3NJtSV-uSPgOagx6d7uNyJ6siygg_sp-E7_VxORpTVz_rpKgf0wKSV8FQ6R-6nQPEapaXXxHOgVv5fDnu6uhNc5wQ-NeDonvTjBHSAP1lAw7GU4hDYQOHOnILHvfW4wCrCx89VY6hxTirRFf3-sKt22KHl6kluVxRjjusrePJXben0mUGVX45uefb8qumd0nB8s3Zo8fNbcHBC1uGycj3q0QV4peuHnrtNZShE6ALX8cgl1QEz44DuGdW9_nI_w7FTHl-uoVHNft5JtqbUtwcIzE7B65atWt3eHTK1VszNcG-4MVvfJgUKd3_Kcx8w-BiRm00 "SHOW_FOOT_BOXES() Sample")
+
+### SHOW_INDEX(?show)
+
+```plantuml
+@startuml
+!include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Sequence.puml
+
+SHOW_INDEX()
+
+Person(admin, "Administrator")
+System_Boundary(c1, 'Sample')
+    Container(web_app, "Web Application", "C#, ASP.NET Core 2.1 MVC", "Allows users to compare multiple Twitter timelines")
+' in a sequence diagram Boundary_End() has to be used instead of  { }
+Boundary_End()
+System(twitter, "Twitter")
+
+Rel(admin, web_app, "Uses", "HTTPS")
+Rel(web_app, twitter, "Gets tweets from", "HTTPS")
+@enduml
+```
+
+![SHOW_INDEX() Sample](https://www.plantuml.com/plantuml/png/LL1DRzD04BtlhnZ28OwKsYhYnAaXH1I9bWYxb9irzawRbVPZsPsLLI7-ExEYeU3Bo3Fluxszoeo9YxFgbV6pBPhWn1ppkwvBkBIFXazbAfdI73oJvtOEheiMVULSPDRMJDt-xSMnhkvkFdSECrEIrTZJZq9-fZPMUTLVVxaVFzr-E7nlDaeTAUNW6zJE-2siTdMQp0avfDL6zK-YuiRteNYDwQcPBxUmxj55I-kD0ldsaWUDfzGiD8qOewZSqmIx6AsPaKtmArdjNszXrn_RsyCWb4Jmfhs4cs_xUjjP6vOCjLq63Y3L8Wh45Sj6d61O34iPOEF8YbUMP6im7X3oSpdG1XyJEZX77GzUDniuOPM4YQgy5exqGGtX0U0d_5B_eSzr6_xZ9z6UdSLFVILxVgQNfdTPmiYy7ePZBwWA-djzaVb8dEMNwdX8mVrBkIAlYxE_0G00 "SHOW_INDEX() Sample")
+
diff --git a/README.md b/README.md
index b7346878..69ebf676 100644
--- a/README.md
+++ b/README.md
@@ -255,7 +255,7 @@ SHOW_LEGEND()
 ### Container diagram
 
   - Import: `!include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Container.puml`
-  - Additional Macros:
+  - Additional Macros  (based on context diagram macros):
     - `Container(alias, label, ?techn, ?descr, ?sprite, ?tags, ?link)`
     - `ContainerDb`
     - `ContainerQueue`
@@ -267,7 +267,7 @@ SHOW_LEGEND()
 ### Component diagram
 
   - Import: `!include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Component.puml`
-  - Additional Macros:
+  - Additional Macros (based on container diagram macros):
     - `Component(alias, label, ?techn, ?descr, ?sprite, ?tags, ?link)`
     - `ComponentDb`
     - `ComponentQueue`
@@ -278,8 +278,7 @@ SHOW_LEGEND()
 ### Dynamic diagram
 
   - Import: `!include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Dynamic.puml`
-  - Additional Macros (based on the component diagram macros):
-    - `RelIndex(index, from, to, label, ?tags, ?link)`
+  - Additional Macros (based on component diagram macros):
     - (lowercase) `increment($offset=1)`: increase current index (procedure which has no direct output)
     - (lowercase) `setIndex($new_index)`: set the new index (procedure which has no direct output)
     - `LastIndex()`: return the last used index (function which can be used as argument)
@@ -288,6 +287,11 @@ SHOW_LEGEND()
     - `Index($offset=1)`: returns current index and calculates next index (function which can be used as argument)
     - `SetIndex($new_index)`: returns new set index and calculates next index (function which can be used as argument)
 
+  -  All relationship macros are extended with `?index= `:
+
+     > All `RelIndex...()` calls are obsolete and can be replaced with calls like Rel($index=..., ...) or Rel(..., $index=).
+     > A full sample see [samples/C4_Dynamic Diagram Sample - message bus.puml](samples/C4_Dynamic%20Diagram%20Sample%20-%20message%20bus.puml)
+
 ### Deployment diagram
 
   - Import: `!include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Deployment.puml`
@@ -311,22 +315,22 @@ but existing elements and relationships can be reused as participants and calls
       - **boundaries have to be defined without `{` and `}`** and instead of `}` the **`Boundary_End()`** macro has to be called
     - Additional (element specific) Macros:
       - `Boundary_End()`
-    - Additional (element specific) Layout Options:
+    - Additional Layout Options:
       - `SHOW_ELEMENT_DESCRIPTIONS(?show)`
       - `SHOW_FOOT_BOXES(?show)`
-    - Only following 3 relationship specific macros are supported:
-      - `Rel($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")`
-      - `RelIndex($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")`
-      - `RelSpecialIndex($rel, $e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")`:
+      - `SHOW_INDEX(?show)`
+    - Only following (extended) relationship specific macros is supported:
+      - `Rel($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="", $rel="")`  
+        `$index` enables the definition of active/next index with e.g. the related index macros below  
         `$rel` enables the definition of all PlantUML specific arrow types, details see e.g.
         [All arrow types](https://plantuml.com/sequence-diagram#4764f83f72ed032f) and
         [Slanted or odd arrows](https://plantuml.com/sequence-diagram#5bd6712206960fab)
-    - The 5 index related macros (like the dynamic diagram)
-      - (lowercase) `increment($offset=1)`: increase current index (procedure which has no direct output)
-      - (lowercase) `setIndex($new_index)`: set the new index (procedure which has no direct output)
-      - `LastIndex()`: return the last used index (function which can be used as argument)
+    - The index related macros (like the dynamic diagram)
       - `Index($offset=1)`: returns current index and calculates next index (function which can be used as argument)
       - `SetIndex($new_index)`: returns new set index and calculates next index (function which can be used as argument)
+      - `LastIndex()`: return the last used index (function which can be used as argument)
+      - (lowercase) `increment($offset=1)`: increase current index (procedure which has no direct output)
+      - (lowercase) `setIndex($new_index)`: set the new index (procedure which has no direct output)
 
   - (Typically additional used) PlantUML statements:
     - [Grouping message](https://plantuml.com/sequence-diagram#425ba4350c02142c)
diff --git a/percy/TestSequenceSkinparams.puml b/percy/TestSequenceSkinparams.puml
index 5c26be5e..e2be6ef2 100644
--- a/percy/TestSequenceSkinparams.puml
+++ b/percy/TestSequenceSkinparams.puml
@@ -71,12 +71,14 @@ sequenceDiagram {
   !include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Sequence.puml
 !endif
 
+SHOW_INDEX(true)
+
 Person(Alice, "Alice")
 Person(Bob, "Bob")
 
 activate Bob
 
-Rel(Alice, Bob, "Authentication Request")
+Rel(Alice, Bob, "Authentication Request", $index = SetIndex(1), $rel= "->(39)")
 
 alt successful case
     Rel(Bob, Alice, "Authentication Accepted")
diff --git a/samples/C4CoreDiagrams.md b/samples/C4CoreDiagrams.md
index e6dcbdfe..885f168a 100644
--- a/samples/C4CoreDiagrams.md
+++ b/samples/C4CoreDiagrams.md
@@ -51,13 +51,13 @@ Source: [C4_Context Diagram Sample - bigbankplc-landscape.puml](C4_Context%20Dia
 
 Source: [C4_Dynamic Diagram Sample - bigbankplc.puml](C4_Dynamic%20Diagram%20Sample%20-%20bigbankplc.puml)
 
-![C4_Dynamic Diagram Sample - bigbankplc](https://www.plantuml.com/plantuml/png/NP9BRnD13CVl-HIcfmIrYO2Ua13Dew95VKHD2k8KUMUTtH7pMDdUHX7YkpEpQPGkDu_7zlytVy-LABAstWtUsM1SMnBKgerydamOT-FAQjqMhH2R69I2ZatqayPXo3qNegMpnMH-UR7CgUVxkub7KUAKsYps0RqruoPF7znDVpq-hpS_RzStcxlhRzSFY-5eC9YdgMW3yQ8OcijpE5kWOe52Pob-8eTgOq07npIiJ4qUy-rA8vD0PWEcoefoLmqsR2FxBZw76gMc4h3Lce9QSoWnJ6K-efDpG6D815oiqe7KZCz69wwX-P2rRAWSNIon8fWsZNkTap6-umkk3Dj60KC9qr2r3ZdVB3c-s984q3c8MqW4S1kKE912WU5t6WhRDfZ36wtkGIEOLZHwOe4NYxd7CkoeW8BZJeXxS9jPR4E9l1yMIM-wlEt1ZU3F060UVHC31HsQJ_abP5fEKgTyvsN36MP667haVRfk7rHcIh5Lo1qsMMng35K-D2YoYroUREp9Vyn2gI-P0Fa979qZVYD__sEUD4J_kvqw5tU7HSjHEmcdi6_fxDNIrLwKV9R_EqZ8cwTkXmVvjl1MvUt-GMEtnjNZm-HclLwkKb_gwd0xn-ReKfMLwUaBKJaSGNRuE3_LTRzNo95HU0zRZlwLU5SJKnS7z0HVu6kdjvZDK_yLXRBrxXy0 "C4_Dynamic Diagram Sample - bigbankplc")
+![C4_Dynamic Diagram Sample - bigbankplc](https://www.plantuml.com/plantuml/png/fLLHRo8t47xdLqpJIWKf0ILgNofLEW9HanC970kA-hIQzHhMgjUsR2-KLltl7IyOd5jUJfU7ZJqQVzytttZC9-VH-gQMlH-4Oh8fELJU6_VRQ6HnFzmANpL5uxXbMdck_93fUcGagd3cplbIYc8q-ULk4KBhrzceHkUvfL0-FIYi1HkQWDwRZV-ShrVvQhx8f_Ftj_uWHjvVLi_vxEcFfxSf1NiBRfrMVTOuhsjkRs5oNjsC8OPl1htiG4Hr_gWRLQ8zzDazPSHaU54RRMlqGgkR0VpR0_gRK0ae5BTzD2PD7XiZ1JicK_mpxj0nAuo_XR7QDX9j28-br7jtbk30QwXHuPQ3hxYmOApU2Cb9sqUsU28d6tU2yPGwEuOYxIranWgrXKUjVGYkAWv62-L1Rm0Puyu1LNPM0U9IQ8UufcoIbrC32Uhrk8F7nWNa9HQ5yAzVMXQBoXbjVOjDwK858hxZohiEhEKXbLGc1IrZBAresHI7y7zYENhkG0MbKZXUGeaUMx8p69Z66krubm-RKlY4QnpsAS_anz7mxMaLbWkhTw8aBcstg8HhZRdRKmW2J4kqGIOaBRjKq-BIhB98-pGblGMwbcvkaKaEzmyix3AlBNVN6zA1JxmZ_DIsbE3ra7sP9TWOdVk7dDjnwmYxlGzINffrTXHBg3Jx1cE99B4rx0BtKsX-t4OfQNM0XMxywPA0hz13XJjE7sEuuYNH_TVhBRdCfyau7qTlRShsHbJ2nR61KCWsK3slLekCJjFHuwHs1oW2NBNzWlGvcx-D4hXyUMKOqux7Eezk2jM2J1ydT3nMqZd_SSeohif4LjFgF9ka0o2wWsAq-4ceal_z-qluzWTtzqU9wmv5D8qQjn6sZfXNmMReV0HyE8cUVNm8kkFx_QgxRqBASztOBb3lvrCG61PGSA1odGUqMzAWeI_5N-rR2rgMGApjqU5mIEbIkW7vv41gjGNXGJZOM-4zLx0Nlefimv1-kWgdKCPFZlrAbdtLplZqVBDFHrU-Al6X0vXEOBGemf59P4dsF7-__3n-8lwcbly3 "C4_Dynamic Diagram Sample - bigbankplc")
 
 ### Sequence Diagram
 
 Source: [C4_Sequence Diagram Sample - bigbankplc.puml](C4_Sequence%20Diagram%20Sample%20-%20bigbankplc.puml)
 
-![C4_Sequence Diagram Sample - bigbankplc](http://www.plantuml.com/plantuml/png/NL9BRnCn4BxdLmmv1PGc0df2GZIFYXRr4NKB7ADPxsJNmXulzhXH_psURQE6tEnvV8_FlaY2KR9tetUMZSiDGIVIfo_pUSJzhBNIvJedYYQm4ClC13_l7RBkd2LfdAtdg_EpZPP-tjxCFIQXM4hRYlvcOaEpNk57gmA0bYbEpCSfZ2lBhQEp3RO4Yxvtrg3OmEFI-e5FM9beUm7a1XRSPeTHEviOdcn32T0v23kGZk2Q2n-JG8tyfu32BhDHA7HMda42c9maU8e9dYpgZesmfnhg6FR5sMpy_aZTTXaoDnYV9tKXN6okZzMLIO1Ly7rWOfcOJuEHbk6QGH5YS8xYMAjzL2stlrRmG4bEkWld2ZLehaaL9iMmN8x_Mrg-MggUIwX-Tah_MOd8v5YCljMFw9U4V9pRIJOFv52eEIZG3SjJC1rogvSUKzg7sAGfa1YbFuIplUHcSXpRkfwOyyAqHi4Q4ochmh-GmQ4CbUd8etOh2P5UCe18hKqITLfps8NeX_CKEamTDO1PEc9vVGOmaHgzeYlIq1XA2LnettIE2lVmprwUADVUIZfU0md3Lwlkx-PNZu-RgYpfZiuFkQxGbIcR5c_CL2n3uCDacHei9t9a13x0BWR_-gRxZY8DPqPFy1M-3MphvQfiZwgh-z_RcyllbtVh4k85SPEz-mS0 "C4_Sequence Diagram Sample - bigbankplc")
+![C4_Sequence Diagram Sample - bigbankplc](https://www.plantuml.com/plantuml/png/NL9BRnCn4BxdLmmv1PGc0df2GZIFYXRr4NKB7ADPxsJNmXulzhXH_psURQE6tEnvV8_FlaY2KR9tetUMZSiDGIVIfo_pUSJzhBNIvJedYYQm4ClC13_l7RBkd2LfdAtdg_EpZPP-tjxCFIQXM4hRYlvcOaEpNk57gmA0bYbEpCSfZ2lBhQEp3RO4Yxvtrg3OmEFI-e5FM9beUm7a1XRSPeTHEviOdcn32T0v23kGZk2Q2n-JG8tyfu32BhDHA7HMda42c9maU8e9dYpgZesmfnhg6FR5sMpy_aZTTXaoDnYV9tKXN6okZzMLIO1Ly7rWOfcOJuEHbk6QGH5YS8xYMAjzL2stlrRmG4bEkWld2ZLehaaL9iMmN8x_Mrg-MggUIwX-Tah_MOd8v5YCljMFw9U4V9pRIJOFv52eEIZG3SjJC1rogvSUKzg7sAGfa1YbFuIplUHcSXpRkfwOyyAqHi4Q4ochmh-GmQ4CbUd8etOh2P5UCe18hKqITLfps8NeX_CKEamTDO1PEc9vVGOmaHgzeYlIq1XA2LnettIE2lVmprwUADVUIZfU0md3Lwlkx-PNZu-RgYpfZiuFkQxGbIcR5c_CL2n3uCDacHei9t9a13x0BWR_-gRxZY8DPqPFy1M-3MphvQfiZwgh-z_RcyllbtVh4k85SPEz-mS0 "C4_Sequence Diagram Sample - bigbankplc")
 
 ### Deployment Diagram
 
diff --git a/samples/C4_Dynamic Diagram Sample - message bus.puml b/samples/C4_Dynamic Diagram Sample - message bus.puml
index 5d88d67d..8bb106e0 100644
--- a/samples/C4_Dynamic Diagram Sample - message bus.puml	
+++ b/samples/C4_Dynamic Diagram Sample - message bus.puml	
@@ -1,4 +1,3 @@
-
 @startuml
 !include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Dynamic.puml
 
@@ -21,12 +20,15 @@ Rel_D(customer, app, "Updates his profile using", "HTTPS")
 Rel(app, customer_service, "Updates customer information using", "JSON/HTTPS")
 Rel_R(customer_service, customer_db, "Stores data in", "JDBC")
 
-RelIndex_D(Index()-1, customer_service, message_bus, "Sends customer update events to", "async")
-RelIndex_U(LastIndex()-2, customer_service, app, "Confirm update to", "async")
+Rel_D(customer_service, message_bus, "Sends customer update events to", "async", $index=Index()-1)
+Rel_U(customer_service, app, "Confirm update to", "async", $index=LastIndex()-2)
+
+Rel_L(message_bus, reporting_service, "Sends customer update events to", "async", $index=Index()-1)
+Rel(reporting_service, reporting_db, "Stores data in", $index=Index()-1)
 
-RelIndex_L(Index()-1, message_bus, reporting_service, "Sends customer update events to", "async")
-RelIndex(Index()-1, reporting_service, reporting_db, "Stores data in")
+' $index cab be first arg too (like the old RelIndex... calls), as long it is written with $index=.... 
+Rel_R($index=SetIndex(5)-2, message_bus, audit_service, "Sends customer update events to", "async")
+Rel($index=Index()-2, audit_service, audit_store, "Stores events in")
 
-RelIndex_R(SetIndex(5)-2, message_bus, audit_service, "Sends customer update events to", "async")
-RelIndex(Index()-2, audit_service, audit_store, "Stores events in")
-@enduml
+SHOW_LEGEND()
+@enduml
\ No newline at end of file