diff --git a/README.md b/README.md
index 922d5ee..ea42787 100644
--- a/README.md
+++ b/README.md
@@ -15,7 +15,7 @@ This package lets you render sequence diagrams directly in Typst. The following
 <td>
 
 ```typst
-#import "@preview/chronos:0.1.0"
+#import "@preview/chronos:0.2.0"
 #chronos.diagram({
   import chronos: *
   _par("Alice")
diff --git a/TODO.md b/TODO.md
index cefe5b4..fa16489 100644
--- a/TODO.md
+++ b/TODO.md
@@ -22,6 +22,7 @@
 - [ ] Add args verification to catch user errors + pretty error messages
 - [ ] PlantUML parser
 - [ ] (Message numbering)
-- [ ] Different types of groups (alt/loop/etc.)
+- [ ] Mainframes
+- [x] Different types of groups (alt/loop/etc.)
 - [ ] Delays
 - [ ] Auto-fit in parent
\ No newline at end of file
diff --git a/docs/example.typ b/docs/example.typ
new file mode 100644
index 0000000..4b614ba
--- /dev/null
+++ b/docs/example.typ
@@ -0,0 +1,39 @@
+#import "../src/lib.typ" as chronos
+
+#let example-preamble = "import \"../src/lib.typ\": *;"
+#let example-scope = (
+  chronos: chronos
+)
+
+#let example(src, show-src: true, vertical: false, fill: true, wrap: true) = {
+  src = src.text
+  let full-src = example-preamble + src
+  let body = eval(full-src, scope: example-scope)
+  let img = if wrap { chronos.diagram(body) } else { body }
+
+  block(width: 100%,
+    align(center,
+      box(
+        stroke: black + 1pt,
+        radius: .5em,
+        fill: if fill {color.white.darken(5%)} else {none},
+        if show-src {
+          let src-block = align(left, raw(src, lang: "typc"))
+          table(
+            columns: if vertical {1} else {2},
+            inset: 1em,
+            align: horizon + center,
+            stroke: none,
+            img,
+            if vertical {table.hline()} else {table.vline()}, src-block
+          )
+        } else {
+          table(
+            inset: 1em,
+            img
+          )
+        }
+      )
+    )
+  )
+}
\ No newline at end of file
diff --git a/docs/examples.typ b/docs/examples.typ
new file mode 100644
index 0000000..a37ab85
--- /dev/null
+++ b/docs/examples.typ
@@ -0,0 +1,155 @@
+#import "example.typ": example
+
+#let seq-comm-align = example(```
+_par("p1", display-name: "Start participant")
+_par("p2", display-name: "End participant")
+let alignments = (
+  "start", "end",
+  "left", "right",
+  "center"
+)
+for a in alignments {
+  _seq(
+    "p2", "p1",
+    comment: raw(a),
+    comment-align: a
+  )
+}
+```)
+
+#let seq-tips = example(```
+let _seq = _seq.with(comment-align: "center")
+_par("a", display-name: "Alice")
+_par("b", display-name: "Bob")
+
+_seq("a", "b", comment: "Various tips", end-tip: "")
+_seq("a", "b", end-tip: ">", comment: `->`)
+_seq("a", "b", end-tip: ">>", comment: `->>`)
+_seq("a", "b", end-tip: "\\", comment: `-\`)
+_seq("a", "b", end-tip: "\\\\", comment: `-\\`)
+_seq("a", "b", end-tip: "/", comment: `-/`)
+_seq("a", "b", end-tip: "//", comment: `-//`)
+_seq("a", "b", end-tip: "x", comment: `->x`)
+_seq("a", "b", start-tip: "x", comment: `x->`)
+_seq("a", "b", start-tip: "o", comment: `o->`)
+_seq("a", "b", end-tip: ("o", ">"), comment: `->o`)
+_seq("a", "b", start-tip: "o",
+               end-tip: ("o", ">"), comment: `o->o`)
+_seq("a", "b", start-tip: ">",
+               end-tip: ">", comment: `<->`)
+_seq("a", "b", start-tip: ("o", ">"),
+               end-tip: ("o", ">"), comment: `o<->o`)
+_seq("a", "b", start-tip: "x",
+               end-tip: "x", comment: `x<->x`)
+_seq("a", "b", end-tip: ("o", ">>"), comment: `->>o`)
+_seq("a", "b", end-tip: ("o", "\\"), comment: `-\o`)
+_seq("a", "b", end-tip: ("o", "\\\\"), comment: `-\\o`)
+_seq("a", "b", end-tip: ("o", "/"), comment: `-/o`)
+_seq("a", "b", end-tip: ("o", "//"), comment: `-//o`)
+_seq("a", "b", start-tip: "x",
+               end-tip: ("o", ">"), comment: `x->o`)
+```)
+
+#let grp = example(```
+_par("a", display-name: "Alice")
+_par("b", display-name: "Bob")
+
+_grp("Group 1", desc: "Description", {
+  _seq("a", "b", comment: "Authentication")
+  _grp("loop", desc: "1000 times", {
+    _seq("a", "b", comment: "DoS Attack")
+  })
+  _seq("a", "b", end-tip: "x")
+})
+```)
+
+#let alt = example(```
+_par("a", display-name: "Alice")
+_par("b", display-name: "Bob")
+
+_alt(
+  "first encounter", {
+    _seq("a", "b", comment: "Who are you ?")
+    _seq("b", "a", comment: "I'm Bob")
+  },
+
+  "know eachother", {
+    _seq("a", "b", comment: "Hello Bob")
+    _seq("b", "a", comment: "Hello Alice")
+  },
+
+  "best friends", {
+    _seq("a", "b", comment: "Hi !")
+    _seq("b", "a", comment: "Hi !")
+  }
+)
+```)
+
+#let loop = example(```
+_par("a", display-name: "Alice")
+_par("b", display-name: "Bob")
+
+_loop("default loop", {
+  _seq("a", "b", comment: "Are you here ?")
+})
+_gap()
+_loop("min loop", min: 1, {
+  _seq("a", "b", comment: "Are you here ?")
+})
+_gap()
+_loop("min-max loop", min: 1, max: 5, {
+  _seq("a", "b", comment: "Are you still here ?")
+})
+```)
+
+#let sync = example(```
+_par("alice", display-name: "Alice")
+_par("bob", display-name: "Bob")
+_par("craig", display-name: "Craig")
+
+_seq("bob", "alice")  // Unsynchronized
+_seq("bob", "craig")  //  "
+_sync({
+  _seq("bob", "alice")  // Synchronized
+  _seq("bob", "craig")  //  "
+})
+_seq("alice", "bob")  // Unsynchronized
+_seq("craig", "bob")  //  "
+_sync({
+  _seq("alice", "bob")  // Synchronized
+  _seq("craig", "bob")  //  "
+})
+```)
+
+#let gaps-seps = example(```
+_par("alice", display-name: "Alice")
+_par("bob", display-name: "Bob")
+
+_seq("alice", "bob", comment: "Hello")
+_gap(size: 10)
+_seq("bob", "alice", comment: "Hi")
+_sep("Another day")
+_seq("alice", "bob", comment: "Hello again")
+```)
+
+#let notes-shapes = example(```
+_par("alice", display-name: "Alice")
+_par("bob", display-name: "Bob")
+_note("over", `default`, pos: "alice")
+_note("over", `rect`, pos: "bob", shape: "rect")
+_note("over", `hex`, pos: ("alice", "bob"), shape: "hex")
+```)
+
+#let notes-sides = example(```
+_par("alice", display-name: "Alice")
+_par("bob", display-name: "Bob")
+_par("charlie", display-name: "Charlie")
+_note("left", [`left` of Alice], pos: "alice")
+_note("right", [`right` of Charlie], pos: "charlie")
+_note("over", [`over` Alice and Bob], pos: ("alice", "bob"))
+_note("across", [`across` all participants])
+_seq("alice", "bob")
+_note("left", [linked with sequence])
+_note("over", [A note], pos: "alice")
+_note("over", [Aligned note], pos: "charlie", aligned: true)
+```, vertical: true)
\ No newline at end of file
diff --git a/docs/gaps_seps.typ b/docs/gaps_seps.typ
new file mode 100644
index 0000000..d569ab9
--- /dev/null
+++ b/docs/gaps_seps.typ
@@ -0,0 +1,8 @@
+/// Creates a gap before the next element
+/// - size (int): Size of the gap
+#let _gap(size: 20) = {}
+
+/// Creates a separator before the next element
+/// #examples.gaps-seps
+/// - name (content): Name to display in the middle of the separator
+#let _sep(name) = {}
\ No newline at end of file
diff --git a/docs/groups.typ b/docs/groups.typ
new file mode 100644
index 0000000..ece4ae7
--- /dev/null
+++ b/docs/groups.typ
@@ -0,0 +1,58 @@
+/// Creates a group of sequences
+/// #examples.grp
+/// - name (content): The group's name
+/// - desc (none, content): Optional description
+/// - type (str): The groups's type (should only be set through other functions like @@_alt() or @@_loop() )
+/// - elmts (array): Elements inside the group (can be sequences, other groups, notes, etc.)
+#let _grp(
+  name,
+  desc: none,
+  type: "default",
+  elmts
+) = {}
+
+/// Creates an alt-else group of sequences
+/// 
+/// It contains at least one section but can have as many as needed
+/// #examples.alt
+/// - desc (content): The alt's label
+/// - elmts (array): Elements inside the alt's first section
+/// - ..args (content, array): Complementary "else" sections.\ You can add as many else sections as you need by passing a content (else section label) followed by an array of elements (see example)
+#let _alt(
+  desc,
+  elmts,
+  ..args
+)
+
+/// Creates a looped group of sequences
+/// #examples.loop
+/// - desc (content): Loop description
+/// - min (none, number): Optional lower bound of the loop
+/// - max (auto, number): Upper bound of the loop. If left as `auto` and `min` is set, it will be infinity (`'*'`)
+/// - elmts (array): Elements inside the group
+#let _loop(
+  desc,
+  min: none,
+  max: auto,
+  elmts
+) = {}
+
+/// Synchronizes multiple sequences\
+/// All elements inside a synchronized group will start at the same time
+/// #examples.sync
+/// - elmts (array): Synchronized elements (generally sequences or notes)
+#let _sync(
+  elmts
+)
+
+/// Creates an optional group\
+/// This is a simple wrapper around @@_grp()
+/// - desc (content): Group description
+/// - elmts (array): Elements inside the group
+#let _opt(desc, elmts) = {}
+
+/// Creates a break group\
+/// This is a simple wrapper around @@_grp()
+/// - desc (content): Group description
+/// - elmts (array): Elements inside the group
+#let _break(desc, elmts) = {}
\ No newline at end of file
diff --git a/docs/notes.typ b/docs/notes.typ
new file mode 100644
index 0000000..3b783eb
--- /dev/null
+++ b/docs/notes.typ
@@ -0,0 +1,23 @@
+/// Creates a note
+/// - side (str): The side on which to place the note (see @@SIDES for accepted values)
+/// - content (content): The note's content
+/// - pos (none, str, array): Optional participant(s) on which to draw next to / over. If `side` is "left" or "right", sets next to which participant the note is placed. If `side` is "over", sets over which participant(s) it is placed
+/// - color (color): The note's color
+/// - shape (str): The note's shape (see @@SHAPES for accepted values)
+/// - aligned (bool): True if the note is aligned with another note, in which case `side` must be `"over"`, false otherwise
+#let _note(
+  side,
+  content,
+  pos: none,
+  color: rgb("#FEFFDD"),
+  shape: "default",
+  aligned: false
+) = {}
+
+/// Accepted values for `shape` argument of @@_note()
+/// #examples.notes-shapes
+#let SHAPES = ("default", "rect", "hex")
+
+/// Accepted values for `side` argument of @@_note()
+/// #examples.notes-sides
+#let SIDES = ("left", "right", "over", "across")
\ No newline at end of file
diff --git a/docs/participants.typ b/docs/participants.typ
new file mode 100644
index 0000000..30db854
--- /dev/null
+++ b/docs/participants.typ
@@ -0,0 +1,69 @@
+/// Possible participant shapes
+/// #box(width: 100%, align(center)[
+///   #chronos.diagram({
+///     import chronos: *
+///     let _par = _par.with(show-bottom: false)
+///     _par("Foo", display-name: "participant", shape: "participant")
+///     _par("Foo1", display-name: "actor", shape: "actor")
+///     _par("Foo2", display-name: "boundary", shape: "boundary")
+///     _par("Foo3", display-name: "control", shape: "control")
+///     _par("Foo4", display-name: "entity", shape: "entity")
+///     _par("Foo5", display-name: "database", shape: "database")
+///     _par("Foo6", display-name: "collections", shape: "collections")
+///     _par("Foo7", display-name: "queue", shape: "queue")
+///     _par("Foo8", display-name: "custom", shape: "custom", custom-image: TYPST)
+///     _gap()
+///   })
+/// ])
+#let SHAPES = (
+  "participant",
+  "actor",
+  "boundary",
+  "control",
+  "entity",
+  "database",
+  "collections",
+  "queue",
+  "custom"
+)
+
+/// Creates a new participant
+/// - name (str): Unique participant name used as reference in other functions
+/// - display-name (auto, content): Name to display in the diagram. If set to `auto`, `name` is used
+/// - from-start (bool): If set to true, the participant is created at the top of the diagram. Otherwise, it is created at the first reference
+/// - invisible (bool): If set to true, the participant will not be shown
+/// - shape (str): The shape of the participant. Possible values in @@SHAPES
+/// - color (color): The participant's color
+/// - custom-image (none, image): If shape is 'custom', sets the custom image to display
+/// - show-bottom (bool): Whether to display the bottom shape
+/// - show-top (bool): Whether to display the top shape
+/// -> array
+#let _par(
+  name,
+  display-name: auto,
+  from-start: true,
+  invisible: false,
+  shape: "participant",
+  color: rgb("#E2E2F0"),
+  custom-image: none,
+  show-bottom: true,
+  show-top: true,
+) = {}
+
+/// Sets some options for columns between participants
+///
+/// Parameters `p1` and `p2` MUST be consecutive participants (also counting found/lost messages), but they do not need to be in the left to right order
+/// - p1 (str): The first neighbouring participant
+/// - p2 (str): The second neighbouring participant
+/// - width (auto, int, float, length): Optional fixed width of the column\ If the column's content (e.g. sequence comments) is larger, it will overflow
+/// - margin (int, float, length): Additional margin to add to the column\ This margin is not included in `width` and `min-width`, but rather added separately
+/// - min-width (int, float, length): Minimum width of the column\ If set to a larger value than `width`, the latter will be overriden
+/// - max-width (int, float, length, none): Maximum width of the column\ If set to a lower value than `width`, the latter will be overriden\ If set to `none`, no restriction is applied
+#let _col(
+  p1,
+  p2,
+  width: auto,
+  margin: 0,
+  min-width: 0,
+  max-width: none
+) = {}
\ No newline at end of file
diff --git a/docs/sequences.typ b/docs/sequences.typ
new file mode 100644
index 0000000..e9be9a6
--- /dev/null
+++ b/docs/sequences.typ
@@ -0,0 +1,60 @@
+/// Manually adds an event to the given participant
+/// - participant (str): The participant concerned by the event
+/// - event (str): The event type (see @@EVENTS for ccepted values)
+#let _evt(participant, event) = {}
+
+/// Creates a sequence / message between two participants
+/// - p1 (str): Start participant
+/// - p2 (str): End participant
+/// - comment (none, content): Optional comment to display along the arrow
+/// - comment-align (str): Where to align the comment with respect to the arrow (see @@comment-align for accepted values)
+/// - dashed (bool): Whether the arrow's stroke is dashed or not
+/// - start-tip (str): Start arrow tip (see @@tips for accepted values)
+/// - end-tip (str): End arrow tip (see @@tips for accepted values)
+/// - color (color): Arrow's color
+/// - flip (bool): If true, the arrow is flipped (goes from end to start). This is particularly useful for self calls, to change the side on which the arrow appears
+/// - enable-dst (bool): If true, enables the destination lifeline
+/// - create-dst (bool): If true, creates the destination lifeline and participant
+/// - disable-dst (bool): If true, disables the destination lifeline
+/// - destroy-dst (bool): If true, destroys the destination lifeline and participant
+/// - disable-src (bool): If true, disables the source lifeline
+/// - destroy-src (bool): If true, destroy the source lifeline and participant
+/// - lifeline-style (auto, dict): Optional styling options for lifeline rectangles (see CeTZ documentation for more information on all possible values)
+/// - slant (none, int): Optional slant of the arrow
+/// -> array
+#let _seq(
+  p1,
+  p2,
+  comment: none,
+  comment-align: "left",
+  dashed: false,
+  start-tip: "",
+  end-tip: ">",
+  color: black,
+  flip: false,
+  enable-dst: false,
+  create-dst: false,
+  disable-dst: false,
+  destroy-dst: false,
+  disable-src: false,
+  destroy-src: false,
+  lifeline-style: auto,
+  slant: none
+) = {}
+
+/// Accepted values for `event` argument of @@_evt()
+/// 
+/// `EVENTS = ("create", "destroy", "enable", "disable")`
+#let EVENTS = ("create", "destroy", "enable", "disable")
+
+/// Accepted values for `start-tip` and `end-tip` arguments of @@_seq()
+/// #examples.seq-tips
+#let tips = (
+  "", ">", ">>", "\\", "\\\\", "/", "//", "x", "o",
+)
+
+/// Accepted values for `comment-align` argument of @@_seq()
+/// #examples.seq-comm-align
+#let comment-align = (
+  "start", "end", "left", "center", "right"
+)
\ No newline at end of file
diff --git a/gallery/example1.pdf b/gallery/example1.pdf
index de434a8..693d6e1 100644
Binary files a/gallery/example1.pdf and b/gallery/example1.pdf differ
diff --git a/gallery/example1.typ b/gallery/example1.typ
index 48be250..89ee3ae 100644
--- a/gallery/example1.typ
+++ b/gallery/example1.typ
@@ -33,15 +33,38 @@ Alice <-- Bob: Another authentication Response
 #chronos.diagram({
   import chronos: *
   _seq("Alice", "Bob", comment: "Authentication Request")
-  _seq("Bob", "Alice", comment: "Authentication Failure")
 
-  _grp("My own label", desc: "My own label2", {
-    _seq("Alice", "Log", comment: "Log attack start")
-    _grp("loop", desc: "1000 times", {
-      _seq("Alice", "Bob", comment: "DNS Attack")
-    })
-    _seq("Alice", "Bob", comment: "Log attack end")
+  _alt(
+    "successful case", {
+      _seq("Bob", "Alice", comment: "Authentication Accepted")
+    },
+    "some kind of failure", {
+      _seq("Bob", "Alice", comment: "Authentication Failure")
+
+      _grp("My own label", desc: "My own label2", {
+        _seq("Alice", "Log", comment: "Log attack start")
+        _loop("1000 times", {
+          _seq("Alice", "Bob", comment: "DNS Attack")
+        })
+        _seq("Alice", "Log", comment: "Log attack end")
+      })
+    },
+    "Another type of failure", {
+      _seq("Bob", "Alice", comment: "Please repeat")
+    }
+  )
+})
+
+#chronos.diagram({
+  import chronos: *
+  _par("a", display-name: box(width: 1.5em, height: .5em), show-bottom: false)
+  _par("b", display-name: box(width: 1.5em, height: .5em), show-bottom: false)
+  _col("a", "b", width: 2cm)
+  _loop("a<1", min: 1, {
+    _seq("a", "b", end-tip: ">>")
+    _seq("b", "a", end-tip: ">>")
   })
+  _seq("a", "b", end-tip: ">>")
 })
 
 #chronos.diagram({
@@ -55,6 +78,15 @@ Alice <-- Bob: Another authentication Response
   _seq("Bob", "Alice", comment: "another authentication Response", dashed: true)
 })
 
+#chronos.diagram({
+  import chronos: *
+  _seq("Alice", "Bob", comment: "Authentication Request")
+  _delay()
+  _seq("Bob", "Alice", comment: "Authentication Response")
+  _delay(name: "5 minutes later")
+  _seq("Bob", "Alice", comment: "Good Bye !")
+})
+
 #chronos.diagram({
   import chronos: *
   _seq("Alice", "Bob", comment: "message 1")
diff --git a/gallery/example2.pdf b/gallery/example2.pdf
index 7b186d7..0861fff 100644
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diff --git a/gallery/example3.pdf b/gallery/example3.pdf
index 7e9f09a..f916e4d 100644
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diff --git a/gallery/example3.typ b/gallery/example3.typ
index 4c48a04..09a4090 100644
--- a/gallery/example3.typ
+++ b/gallery/example3.typ
@@ -144,4 +144,23 @@ chronos.diagram({
   _par("d", display-name: "Danny", show-bottom: false, show-top: false)
 
   _gap()
+})
+
+#chronos.diagram({
+  import chronos: *
+
+  _par("a", display-name: "Alice")
+  _par("b", display-name: "Bob")
+  _par("c", display-name: "Caleb")
+  _par("d", display-name: "Danny")
+  _par("e", display-name: "Erika")
+
+  _col("a", "b")
+  _col("b", "c", width: 2cm)
+  _col("c", "d", margin: .5cm)
+  _col("d", "e", min-width: 2cm)
+
+  //_seq("b", "c", comment: [Hello World !])
+  //_seq("c", "d", comment: [Hello World])
+  //_seq("d", "e", comment: [Hello World])
 })
\ No newline at end of file
diff --git a/gallery/notes.pdf b/gallery/notes.pdf
index 8030aea..2ff99fd 100644
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diff --git a/gallery/readme/boilerplate.png b/gallery/readme/boilerplate.png
index 04af7e8..755b523 100644
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diff --git a/gallery/readme/lifelines.png b/gallery/readme/lifelines.png
index ffb48ec..fbd5bcf 100644
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diff --git a/gallery/readme/simple_sequence.png b/gallery/readme/simple_sequence.png
index 1af1870..f771ad5 100644
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diff --git a/manual.pdf b/manual.pdf
new file mode 100644
index 0000000..dca8906
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diff --git a/manual.typ b/manual.typ
new file mode 100644
index 0000000..69e96c7
--- /dev/null
+++ b/manual.typ
@@ -0,0 +1,214 @@
+#import "@preview/tidy:0.3.0"
+#import "src/lib.typ" as chronos
+#import "src/participant.typ" as mod-par
+#import "docs/examples.typ"
+#import "docs/example.typ": example
+
+#let TYPST = image("gallery/typst.png", width: 1.5cm, height: 1.5cm, fit: "contain")
+
+#let doc-ref(target, full: false, var: false) = {
+  let (module, func) = target.split(".")
+  let label-name = module + func
+  let display-name = func
+  if full {
+    display-name = target
+  }
+  if not var {
+    label-name += "()"
+    display-name += "()"
+  }
+  link(label(label-name))[#display-name]
+}
+
+#set heading(numbering: (..num) => if num.pos().len() < 4 {
+  numbering("1.1", ..num)
+})
+#{
+  outline(indent: true, depth: 3)
+}
+#show link: set text(fill: blue)
+
+#set page(numbering: "1/1", header: align(right)[chronos #sym.dash.em v#chronos.version])
+#set page(
+  header: align(left)[chronos #sym.dash.em v#chronos.version],
+  footer: context align(center, counter(page).display("1/1", both: true))
+)
+
+= Introduction
+
+This package lets you create nice sequence diagrams using the CeTZ package.
+
+= Usage
+
+Simply import #link("https://typst.app/universe/package/chronos/")[chronos] and call the `diagram` function:
+#pad(left: 1em)[```typ
+#import "@preview/chronos:0.1.0"
+#chronos.diagram({
+  import chronos: *
+  ...
+})
+```]
+
+= Examples
+
+You can find the following examples and more in the #link("https://git.kb28.ch/HEL/circuiteria/src/branch/main/gallery")[gallery] directory
+
+== Some groups and sequences
+
+#example(```
+chronos.diagram({
+  import chronos: *
+  _seq("Alice", "Bob", comment: "Authentication Request")
+  _seq("Bob", "Alice", comment: "Authentication Failure")
+
+  _grp("My own label", desc: "My own label2", {
+    _seq("Alice", "Log", comment: "Log attack start")
+    _grp("loop", desc: "1000 times", {
+      _seq("Alice", "Bob", comment: "DNS Attack")
+    })
+    _seq("Alice", "Bob", comment: "Log attack end")
+  })
+})
+```, wrap: false, vertical: true)
+
+#pagebreak(weak: true)
+
+== Lifelines
+
+#example(```
+chronos.diagram({
+  import chronos: *
+  _seq("alice", "bob", comment: "hello", enable-dst: true)
+  _seq("bob", "bob", comment: "self call", enable-dst: true)
+  _seq(
+    "bill", "bob",
+    comment: "hello from thread 2",
+    enable-dst: true,
+    lifeline-style: (fill: rgb("#005500"))
+  )
+  _seq("bob", "george", comment: "create", create-dst: true)
+  _seq(
+    "bob", "bill",
+    comment: "done in thread 2",
+    disable-src: true,
+    dashed: true
+  )
+  _seq("bob", "bob", comment: "rc", disable-src: true, dashed: true)
+  _seq("bob", "george", comment: "delete", destroy-dst: true)
+  _seq("bob", "alice", comment: "success", disable-src: true, dashed: true)
+})
+```, wrap: false, vertical: true)
+
+#pagebreak(weak: true)
+
+== Found and lost messages
+
+#example(```
+chronos.diagram({
+  import chronos: *
+  _seq("?", "Alice", comment: [?->\ *short* to actor1])
+  _seq("[", "Alice", comment: [\[->\ *from start* to actor1])
+  _seq("[", "Bob", comment: [\[->\ *from start* to actor2])
+  _seq("?", "Bob", comment: [?->\ *short* to actor2])
+  _seq("Alice", "]", comment: [->\]\ from actor1 *to end*])
+  _seq("Alice", "?", comment: [->?\ *short* from actor1])
+  _seq("Alice", "Bob", comment: [->\ from actor1 to actor2])
+})
+```, wrap: false, vertical: true)
+
+#pagebreak(weak: true)
+
+== Custom images
+
+#example(```
+let load-img(path) = image(path, width: 1.5cm, height: 1.5cm, fit:"contain")
+let TYPST = load-img("../gallery/typst.png")
+let FERRIS = load-img("../gallery/ferris.png")
+let ME = load-img("../gallery/me.jpg")
+
+chronos.diagram({
+  import chronos: *
+  _par("me", display-name: "Me", shape: "custom", custom-image: ME)
+  _par("typst", display-name: "Typst", shape: "custom", custom-image: TYPST)
+  _par("rust", display-name: "Rust", shape: "custom", custom-image: FERRIS)
+
+  _seq("me", "typst", comment: "opens document", enable-dst: true)
+  _seq("me", "typst", comment: "types document")
+  _seq("typst", "rust", comment: "compiles content", enable-dst: true)
+  _seq("rust", "typst", comment: "renders document", disable-src: true)
+  _seq("typst", "me", comment: "displays document", disable-src: true)
+})
+```, wrap: false, vertical: true)
+
+#pagebreak(weak: true)
+
+= Reference
+
+#let par-docs = tidy.parse-module(
+  read("docs/participants.typ"),
+  name: "Participants",
+  require-all-parameters: true,
+  scope: (
+    chronos: chronos,
+    mod-par: mod-par,
+    TYPST: TYPST,
+    doc-ref: doc-ref
+  )
+)
+#tidy.show-module(par-docs, show-outline: false, sort-functions: none)
+
+#pagebreak(weak: true)
+
+#let seq-docs = tidy.parse-module(
+  read("docs/sequences.typ"),
+  name: "Sequences",
+  require-all-parameters: true,
+  scope: (
+    chronos: chronos,
+    doc-ref: doc-ref,
+    examples: examples
+  )
+)
+#tidy.show-module(seq-docs, show-outline: false, sort-functions: none)
+
+#pagebreak(weak: true)
+
+#let grp-docs = tidy.parse-module(
+  read("docs/groups.typ"),
+  name: "Groups",
+  require-all-parameters: true,
+  scope: (
+    chronos: chronos,
+    doc-ref: doc-ref,
+    examples: examples
+  )
+)
+#tidy.show-module(grp-docs, show-outline: false, sort-functions: none)
+
+#pagebreak(weak: true)
+
+#let gap-sep-docs = tidy.parse-module(
+  read("docs/gaps_seps.typ"),
+  name: "Gaps and separators",
+  require-all-parameters: true,
+  scope: (
+    chronos: chronos,
+    doc-ref: doc-ref,
+    examples: examples
+  )
+)
+#tidy.show-module(gap-sep-docs, show-outline: false)
+
+#pagebreak(weak: true)
+
+#let notes-docs = tidy.parse-module(
+  read("docs/notes.typ"),
+  name: "Notes",
+  require-all-parameters: true,
+  scope: (
+    chronos: chronos,
+    doc-ref: doc-ref,
+    examples: examples
+  )
+)
+#tidy.show-module(notes-docs, show-outline: false)
diff --git a/src/diagram.typ b/src/diagram.typ
index fbba74a..b286ffc 100644
--- a/src/diagram.typ
+++ b/src/diagram.typ
@@ -1,6 +1,7 @@
 #import "utils.typ": get-group-span, fit-canvas
 #import "renderer.typ": render
 #import "participant.typ" as participant: _par, PAR-SPECIALS
+#import "sequence.typ": _seq
 
 #let _gap(size: 20) = {
   return ((
@@ -18,6 +19,18 @@
   ),)
 }
 
+#let _col(p1, p2, width: auto, margin: 0, min-width: 0, max-width: none) = {
+  return ((
+    type: "col",
+    p1: p1,
+    p2: p2,
+    width: width,
+    margin: margin,
+    min-width: min-width,
+    max-width: max-width
+  ),)
+}
+
 #let diagram(elements, width: auto) = {
   if elements == none {
     return
@@ -27,7 +40,9 @@
   let elmts = elements
   let i = 0
 
-  // Flatten groups
+  let activation-history = ()
+
+  // Flatten groups + convert returns
   while i < elmts.len() {
     let elmt = elmts.at(i)
     if elmt.type == "grp" {
@@ -51,6 +66,30 @@
         ),) +
         elmts.slice(i+1)
       )
+    } else if elmt.type == "seq" {
+      if elmt.enable-dst {
+        activation-history.push(elmt)
+      }
+    } else if elmt.type == "evt" {
+      if elmt.event == "enable" {
+        for elmt2 in elmts.slice(0, i).rev() {
+          if elmt2.type == "seq" {
+            activation-history.push(elmt2)
+            break
+          }
+        }
+      }
+    } else if elmt.type == "ret" {
+      if activation-history.len() == 0 {
+        panic("Cannot return if no lifeline is activated")
+      }
+      let seq = activation-history.pop()
+      elmts.at(i) = _seq(
+        seq.p2, seq.p1,
+        comment: elmt.comment,
+        disable-src: true,
+        dashed: true
+      ).first()
     }
     i += 1
   }
@@ -119,6 +158,21 @@
       } else if elmt.side == "right" {
         linked.push("]")
       }
+
+      let pars = none
+      if type(elmt.pos) == str {
+        pars = (elmt.pos,)
+      } else if type(elmt.pos) == array {
+        pars = elmt.pos
+      }
+      if pars != none {
+        for par in pars {
+          if not participant._exists(participants, par) {
+            participants.push(_par(par).first())
+          }
+        }
+      }
+
       last-note = (
         elmt: elmt,
         i: i
@@ -174,7 +228,7 @@
 
   // Compute groups spans (horizontal)
   for (i, elmt) in elmts.enumerate() {
-    if elmt.type == "grp" {
+    if elmt.type == "grp" or elmt.type == "alt" {
       let (min-i, max-i) = get-group-span(participants, elmt)
       elmts.at(i).insert("min-i", min-i)
       elmts.at(i).insert("max-i", max-i)
@@ -187,7 +241,6 @@
     }
   }
 
-  set text(font: "Source Sans 3")
   let canvas = render(participants, elmts)
   fit-canvas(canvas, width: width)
 }
diff --git a/src/group.typ b/src/group.typ
index 78e00c7..821b0cb 100644
--- a/src/group.typ
+++ b/src/group.typ
@@ -1,4 +1,4 @@
-#import "@preview/cetz:0.2.2": draw
+#import "@preview/cetz:0.3.1": draw
 #import "consts.typ": *
 
 #let _grp(name, desc: none, type: "default", elmts) = {
@@ -11,6 +11,36 @@
   ),)
 }
 
+#let _alt(desc, elmts, ..args) = {
+  let all-elmts = ()
+  all-elmts += elmts
+  let args = args.pos()
+  for i in range(0, args.len(), step: 2) {
+    let else-desc = args.at(i)
+    let else-elmts = args.at(i + 1, default: ())
+    all-elmts.push((
+      type: "else",
+      desc: else-desc
+    ))
+    all-elmts += else-elmts
+  }
+
+  return _grp("alt", desc: desc, type: "alt", all-elmts)
+}
+
+#let _loop(desc, min: none, max: auto, elmts) = {
+  let name = "loop"
+  if min != none {
+    if max == auto {
+      max = "*"
+    }
+    name += "(" + str(min) + "," + str(max) + ")"
+  }
+  _grp(name, desc: desc, type: "loop", elmts)
+}
+#let _opt(desc, elmts) = grp("opt", desc: desc, type: "opt", elmts)
+#let _break(desc, elmts) = grp("break", desc: desc, type: "break", elmts)
+
 #let render(x0, x1, y0, y1, group) = {
   let shapes = ()
   let name = text(group.name, weight: "bold")
@@ -50,5 +80,20 @@
     )
   }
 
+  return shapes
+}
+
+#let render-else(x0, x1, y, elmt) = {
+  let shapes = draw.line(
+    (x0, y),
+    (x1, y),
+    stroke: (dash: (2pt, 1pt), thickness: .5pt)
+  )
+  shapes += draw.content(
+    (x0, y),
+    text([\[#elmt.desc\]], weight: "bold", size: .8em),
+    anchor: "north-west",
+    padding: 3pt
+  )
   return shapes
 }
\ No newline at end of file
diff --git a/src/lib.typ b/src/lib.typ
index ec5d651..25671e5 100644
--- a/src/lib.typ
+++ b/src/lib.typ
@@ -1,8 +1,9 @@
-#import "diagram.typ": diagram, from-plantuml, _gap, _evt
+#let version = version(0, 2, 0)
+#import "diagram.typ": diagram, from-plantuml, _gap, _evt, _col
 
-#import "sequence.typ": _seq
-#import "group.typ": _grp
+#import "sequence.typ": _seq, _ret
+#import "group.typ": _grp, _loop, _alt, _opt, _break
 #import "participant.typ": _par
-#import "separator.typ": _sep
+#import "separator.typ": _sep, _delay
 #import "note.typ": _note
 #import "sync.typ": _sync
\ No newline at end of file
diff --git a/src/note.typ b/src/note.typ
index 454d20b..feaa5eb 100644
--- a/src/note.typ
+++ b/src/note.typ
@@ -1,4 +1,4 @@
-#import "@preview/cetz:0.2.2": draw
+#import "@preview/cetz:0.3.1": draw
 #import "consts.typ": *
 
 #let SIDES = (
@@ -25,6 +25,9 @@
       panic("Aligned notes can only be over a participant (got side '" + side + "')")
     }
   }
+  if color == auto {
+    color = COL-NOTE
+  }
   return ((
     type: "note",
     side: side,
diff --git a/src/participant.typ b/src/participant.typ
index d1ec7ef..26e4a7e 100644
--- a/src/participant.typ
+++ b/src/participant.typ
@@ -1,4 +1,4 @@
-#import "@preview/cetz:0.2.2": draw
+#import "@preview/cetz:0.3.1": draw
 #import "consts.typ": *
 
 #let PAR-SPECIALS = "?[]"
@@ -13,6 +13,7 @@
   "queue",
   "custom"
 )
+#let DEFAULT-COLOR = rgb("#E2E2F0")
 
 #let _par(
   name,
@@ -20,11 +21,14 @@
   from-start: true,
   invisible: false,
   shape: "participant",
-  color: rgb("#E2E2F0"),
+  color: DEFAULT-COLOR,
   custom-image: none,
   show-bottom: true,
   show-top: true,
 ) = {
+  if color == auto {
+    color = DEFAULT-COLOR
+  }
   return ((
     type: "par",
     name: name,
diff --git a/src/renderer.typ b/src/renderer.typ
index ace3830..9938e64 100644
--- a/src/renderer.typ
+++ b/src/renderer.typ
@@ -1,5 +1,5 @@
-#import "@preview/cetz:0.2.2": canvas, draw
-#import "utils.typ": get-participants-i, get-style
+#import "@preview/cetz:0.3.1": canvas, draw
+#import "utils.typ": get-participants-i, get-style, normalize-units
 #import "group.typ"
 #import "participant.typ"
 #import participant: PAR-SPECIALS
@@ -194,6 +194,40 @@
     }
     widths.at(i) = w
   }
+
+  for elmt in elements {
+    if elmt.type == "col" {
+      let i1 = pars-i.at(elmt.p1)
+      let i2 = pars-i.at(elmt.p2)
+      if calc.abs(i1 - i2) != 1 {
+        let i-min = calc.min(i1, i2)
+        let i-max = calc.max(i1, i2)
+        let others = pars-i.pairs()
+                           .sorted(key: p => p.last())
+                           .slice(i-min + 1, i-max)
+                           .map(p => "'" + p.first() + "'")
+                           .join(", ")
+        panic(
+          "Column participants must be consecutive (participants (" +
+          others +
+          ") are in between)"
+        )
+      }
+      let i = calc.min(i1, i2)
+
+      if elmt.width != auto {
+        widths.at(i) = normalize-units(elmt.width)
+      }
+
+      let width = widths.at(i)
+      width = calc.max(width, normalize-units(elmt.min-width))
+      if elmt.max-width != none {
+        width = calc.min(width, normalize-units(elmt.max-width))
+      }
+      widths.at(i) = width + normalize-units(elmt.margin)
+    }
+  }
+
   return widths
 }
 
@@ -211,6 +245,7 @@
 
   let draw-seq = sequence.render.with(pars-i, x-pos, participants)
   let draw-group = group.render.with()
+  let draw-else = group.render-else.with()
   let draw-sep = separator.render.with(x-pos)
   let draw-par = participant.render.with(x-pos)
   let draw-note = note.render.with(pars-i, x-pos)
@@ -252,6 +287,9 @@
         if g.at(1).max-i == elmt.max-i { g.at(3) += 1 }
         g
       })
+      if elmt.grp-type == "alt" {
+        elmt.insert("elses", ())
+      }
       groups.push((y, elmt, 0, 0))
       y -= m.height / 1pt
     
@@ -263,6 +301,21 @@
       let x1 = x-pos.at(group.max-i) + end-lvl * 10 + 20
       shapes += draw-group(x0, x1, start-y, y, group)
 
+      if group.grp-type == "alt" {
+        for (else-y, else-elmt) in group.elses {
+          shapes += draw-else(x0, x1, else-y, else-elmt)
+        }
+      }
+
+    // Alt's elses -> reserve space for label + store position
+    } else if elmt.type == "else" {
+      y -= Y-SPACE
+      let m = measure(text([\[#elmt.desc\]], weight: "bold", size: .8em))
+      groups.last().at(1).elses.push((
+        y, elmt
+      ))
+      y -= m.height / 1pt
+
     // Separator
     } else if elmt.type == "sep" {
       let shps
@@ -272,6 +325,26 @@
     // Gap
     } else if elmt.type == "gap" {
       y -= elmt.size
+
+    // Delay
+    } else if elmt.type == "delay" {
+      let y0 = y
+      let y1 = y - elmt.size
+      for (i, line) in lifelines.enumerate() {
+        line.lines.push(("delay-start", y0))
+        line.lines.push(("delay-end", y1))
+        lifelines.at(i) = line
+      }
+      if elmt.name != none {
+        let x0 = x-pos.first()
+        let x1 = x-pos.last()
+        shapes += draw.content(
+          ((x0 + x1) / 2, (y0 + y1) / 2),
+          anchor: "center",
+          elmt.name
+        )
+      }
+      y = y1
     
     // Event
     } else if elmt.type == "evt" {
@@ -385,6 +458,28 @@
           if event == "destroy" {
             destructions.push((x + lvl * LIFELINE-W / 2, line.at(1)))
           }
+        } else if event == "delay-start" {
+          draw.line(
+            (x, last-y),
+            (x, line.at(1)),
+            stroke: (
+              dash: "dashed",
+              paint: gray.darken(40%),
+              thickness: .5pt
+            )
+          )
+          last-y = line.at(1)
+        } else if event == "delay-end" {
+          draw.line(
+            (x, last-y),
+            (x, line.at(1)),
+            stroke: (
+              dash: "loosely-dotted",
+              paint: gray.darken(40%),
+              thickness: .8pt
+            )
+          )
+          last-y = line.at(1)
         }
       }
 
diff --git a/src/separator.typ b/src/separator.typ
index a203bc8..c51b65f 100644
--- a/src/separator.typ
+++ b/src/separator.typ
@@ -1,4 +1,4 @@
-#import "@preview/cetz:0.2.2": draw
+#import "@preview/cetz:0.3.1": draw
 #import "consts.typ": *
 
 #let _sep(name) = {
@@ -8,6 +8,14 @@
   ),)
 }
 
+#let _delay(name: none, size: 30) = {
+  return ((
+    type: "delay",
+    name: name,
+    size: size
+  ),)
+}
+
 #let render(x-pos, elmt, y) = {
   let shapes = ()
   y -= Y-SPACE
diff --git a/src/sequence.typ b/src/sequence.typ
index 4d2f735..4c20ae1 100644
--- a/src/sequence.typ
+++ b/src/sequence.typ
@@ -1,9 +1,12 @@
-#import "@preview/cetz:0.2.2": draw, vector
+#import "@preview/cetz:0.3.1": draw, vector
 #import "consts.typ": *
 #import "participant.typ"
 #import "note.typ"
 
 #let get-arrow-marks(sym, color) = {
+  if sym == none {
+    return none
+  }
   if type(sym) == array {
     return sym.map(s => get-arrow-marks(s, color))
   }
@@ -85,24 +88,39 @@
   ),)
 }
 
+#let _ret(comment: none) = {
+  return ((
+    type: "ret",
+    comment: comment
+  ),)
+}
+
 #let render(pars-i, x-pos, participants, elmt, y, lifelines) = {
   let shapes = ()
 
   y -= Y-SPACE
 
+  let i1 = pars-i.at(elmt.p1)
+  let i2 = pars-i.at(elmt.p2)
+  let width = calc.abs(x-pos.at(i1) - x-pos.at(i2))
+
   let h = 0
+  let comment = if elmt.comment == none {none} else {
+    let w = calc.min(width * 1pt, measure(elmt.comment).width)
+    box(
+      width: if i1 == i2 {auto} else {w},
+      elmt.comment
+    )
+  }
   // Reserve space for comment
-  if elmt.comment != none {
-    h = calc.max(h, measure(box(elmt.comment)).height / 1pt + 6)
+  if comment != none {
+    h = calc.max(h, measure(comment).height / 1pt + 6)
   }
   if "linked-note" in elmt {
     h = calc.max(h, note.get-size(elmt.linked-note).height / 2)
   }
   y -= h
 
-  let i1 = pars-i.at(elmt.p1)
-  let i2 = pars-i.at(elmt.p2)
-
   let start-info = (
     i: i1,
     x: x-pos.at(i1),
@@ -159,7 +177,7 @@
     let m = measure(box(par.display-name))
     let f = if i1 > i2 {-1} else {1}
     end-info.x -= (m.width + PAR-PAD.last() * 2) / 2pt * f
-    shapes += participant.render(x-pos, par, y: end-info.y - CREATE-OFFSET)
+    shapes += participant.render(x-pos, par, y: end-info.y)
   }
 
   end-info.ll-lvl = lifelines.at(i2).level * LIFELINE-W / 2
@@ -234,7 +252,7 @@
       (x2, end-info.y)
     )
 
-    if elmt.comment != none {
+    if comment != none {
       comment-anchor = (
         start: if x-mid < x1 {"south-east"} else {"south-west"},
         end: if x-mid < x1 {"south-west"} else {"south-east"},
@@ -258,7 +276,7 @@
       (x2, end-info.y)
     )
 
-    if elmt.comment != none {
+    if comment != none {
       let start-pt = pts.first()
       let end-pt = pts.last()
       if elmt.start-tip != "" {
@@ -294,7 +312,7 @@
 
   // Start circle tip
   if is-circle-tip(elmt.start-tip) {
-    shapes += draw.circle(pts.first(), radius: CIRCLE-TIP-RADIUS, stroke: elmt.color, fill: none, name: "_circle-start-tip")
+    shapes += draw.circle(pts.first(), radius: CIRCLE-TIP-RADIUS, stroke: none, fill: elmt.color, name: "_circle-start-tip")
     pts.at(0) = "_circle-start-tip"
   
   // Start cross tip
@@ -316,7 +334,7 @@
 
   // End circle tip
   if is-circle-tip(elmt.end-tip) {
-    shapes += draw.circle(pts.last(), radius: 3, stroke: elmt.color, fill: none, name: "_circle-end-tip")
+    shapes += draw.circle(pts.last(), radius: 3, stroke: none, fill: elmt.color, name: "_circle-end-tip")
     pts.at(pts.len() - 1) = "_circle-end-tip"
   
   // End cross tip
@@ -338,27 +356,26 @@
 
   shapes += draw.line(..pts, ..style)
 
-  if elmt.comment != none {
+  if comment != none {
     shapes += draw.content(
       comment-pt,
-      elmt.comment,
+      comment,
       anchor: comment-anchor,
       angle: comment-angle,
       padding: 3pt
     )
   }
 
+  if elmt.create-dst {
+    let dst-line = lifelines.at(i2)
+    dst-line.lines.push(("create", end-info.y))
+    lifelines.at(i2) = dst-line
+  }
   if elmt.enable-dst {
     let dst-line = lifelines.at(i2)
     dst-line.lines.push(("enable", end-info.y, elmt.lifeline-style))
     lifelines.at(i2) = dst-line
   }
-  if elmt.create-dst {
-    end-info.y -= CREATE-OFFSET
-    let dst-line = lifelines.at(i2)
-    dst-line.lines.push(("create", end-info.y))
-    lifelines.at(i2) = dst-line
-  }
 
   if "linked-note" in elmt {
     let m = note.get-size(elmt.linked-note)
diff --git a/src/utils.typ b/src/utils.typ
index 219501c..a97a3b5 100644
--- a/src/utils.typ
+++ b/src/utils.typ
@@ -1,3 +1,12 @@
+#let normalize-units(value) = {
+  if type(value) == int or type(value) == float {
+    return value
+  }
+  if type(value) == length {
+    return value / 1pt
+  }
+  panic("Unsupported type '" + str(type(value)) + "'")
+}
 #let get-participants-i(participants) = {
   let pars-i = (:)
   for (i, p) in participants.enumerate() {
diff --git a/typst.toml b/typst.toml
index ecf0ff9..f11f016 100644
--- a/typst.toml
+++ b/typst.toml
@@ -1,7 +1,7 @@
 [package]
 name = "chronos"
-version = "0.1.0"
-compiler = "0.11.0"
+version = "0.2.0"
+compiler = "0.12.0"
 repository = "https://git.kb28.ch/HEL/chronos"
 entrypoint = "src/lib.typ"
 authors = [
@@ -11,4 +11,4 @@ categories = ["visualization"]
 license = "Apache-2.0"
 description = "A package to draw sequence diagrams with CeTZ"
 keywords = ["sequence", "diagram", "plantuml"]
-exclude = [ "gallery", "gallery.bash" ]
+exclude = [ "gallery", "gallery.bash", "docs" ]