diff --git a/TODO.md b/TODO.md
index cefe5b4..77e47f9 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)
+- [ ] Mainframes
 - [ ] Different types of groups (alt/loop/etc.)
 - [ ] Delays
 - [ ] Auto-fit in parent
\ No newline at end of file
diff --git a/docs/participants.typ b/docs/participants.typ
index d6cd62c..c9aea7a 100644
--- a/docs/participants.typ
+++ b/docs/participants.typ
@@ -48,4 +48,20 @@
   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
+#let _col(
+  p1,
+  p2,
+  width: auto,
+  margin: 0,
+  min-width: 0
 ) = {}
\ No newline at end of file
diff --git a/gallery/example3.pdf b/gallery/example3.pdf
index 7e9f09a..f6c5c11 100644
Binary files a/gallery/example3.pdf and b/gallery/example3.pdf differ
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/manual.pdf b/manual.pdf
index e950552..cccf85c 100644
Binary files a/manual.pdf and b/manual.pdf differ
diff --git a/manual.typ b/manual.typ
index bc888a1..557ecf6 100644
--- a/manual.typ
+++ b/manual.typ
@@ -155,7 +155,7 @@ chronos.diagram({
     doc-ref: doc-ref
   )
 )
-#tidy.show-module(par-docs, show-outline: false)
+#tidy.show-module(par-docs, show-outline: false, sort-functions: none)
 
 #pagebreak(weak: true)
 
diff --git a/src/diagram.typ b/src/diagram.typ
index fbba74a..b70eef5 100644
--- a/src/diagram.typ
+++ b/src/diagram.typ
@@ -18,6 +18,17 @@
   ),)
 }
 
+#let _col(p1, p2, width: auto, margin: 0, min-width: 0) = {
+  return ((
+    type: "col",
+    p1: p1,
+    p2: p2,
+    width: width,
+    margin: margin,
+    min-width: min-width
+  ),)
+}
+
 #let diagram(elements, width: auto) = {
   if elements == none {
     return
diff --git a/src/lib.typ b/src/lib.typ
index 0317a12..6afc60f 100644
--- a/src/lib.typ
+++ b/src/lib.typ
@@ -1,5 +1,5 @@
 #let version = version(0, 1, 1)
-#import "diagram.typ": diagram, from-plantuml, _gap, _evt
+#import "diagram.typ": diagram, from-plantuml, _gap, _evt, _col
 
 #import "sequence.typ": _seq
 #import "group.typ": _grp
diff --git a/src/renderer.typ b/src/renderer.typ
index ace3830..a772654 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 "utils.typ": get-participants-i, get-style, normalize-units
 #import "group.typ"
 #import "participant.typ"
 #import participant: PAR-SPECIALS
@@ -194,6 +194,37 @@
     }
     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)
+      }
+      widths.at(i) = calc.max(
+        widths.at(i),
+        normalize-units(elmt.min-width)
+      ) + normalize-units(elmt.margin)
+    }
+  }
+
   return widths
 }
 
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() {