diff --git a/doc/owlps-aggregatord.t2t b/doc/owlps-aggregatord.t2t
index 00adad3..bbda9ef 100644
--- a/doc/owlps-aggregatord.t2t
+++ b/doc/owlps-aggregatord.t2t
@@ -68,6 +68,9 @@ is first seen:
   When the delay has passed, the request is deleted from the memory.
 
 
+This process is illustrated in the section “**Sequence diagram**” below.
+
+
 When using autocalibration, OwlPS Aggregator also acts as a scheduler
 for the transmission of the autocalibration requests. The capture points
 from which a //hello// message was received are registered and, if at
@@ -200,6 +203,77 @@ If unknown, the coordinates are set to “0.00” and the orientation to
 
 
 
+= Sequence diagram =
+
+This sequence diagram of the positioning process of OwlPS illustrates
+the two-timer mechanism of OwlPS Aggregator. In this example, the mobile
+terminal (Client) transmits a positioning request; a capture point
+(Listener) captures it and forwards it to the aggregation server
+(Aggregator) along with the measured signal strength (SS). When it
+receives this message, the aggregation server starts the aggregation
+timer; shortly after, it receives another message corresponding to the
+same request, which it stores along with the first message (“added”).
+Once the timeout is reached, the aggregation server forwards the
+information of both messages to the positioning server (Positioner)
+– which starts immediately to compute the mobile terminal's position –
+and starts the keep timer. While this timer is still running, it
+receives a new message corresponding to the same request; this time, the
+message is ignored. Would it receive again a new message corresponding to
+the same request after the timeout, it would however consider it as a
+new request and would start a new aggregation timer. Note that it
+doesn't matter whether or not the three messages come from different
+capture points.
+
+```
+,------.          ,--------.        ,----------.              ,----------.
+|Client|          |Listener|        |Aggregator|              |Positioner|
+`--+---'          `---+----'        `----+-----'              `----+-----'
+  ,-.  positioning   ,-.                 |                         |
+  | | -------------->| |                 |                         |
+  | |    request     | |                 |                         |
+  | |                | |  request + SS  ,-.                        |
+  | |                | |--------------->| |  ----. aggregation     |
+  | |                | |                | |      | timer           |
+  | |                | |                | ,-.<---'                 |
+  | |                | |                | |T|                      |
+  | |                | |                | |T|                      |
+  | |                | |                | |T|                      |
+  | |                | |  request + SS  | |T|  ,------.            |
+  | |                | |- - - - - - - ->| |T|  |added  \           |
+  | |                | |                | |T|  `-------'           |
+  | |                | |                | |T|                      |
+  | |                | |                | |T|----.                 |
+  | |                | |                | |T|    | timeout         |
+  | |                | |                | `-'<---'                 |
+  | |                | |                | |  aggregated request   ,-.
+  | |                | |                | |---------------------->| |
+  | |                | |                | | -----.                | |
+  | |                | |                | |      | keep timer     | |
+  | |                | |                | ,-.<---'                | |
+  | |                | |                | |T|                     | |
+  | |                | |                | |T|                     | |
+  | |                | |                | |T|                     | |
+  | |                | |  request + SS  | |T|  ,--------.         | |
+  | |                | |- - - - - - - ->| |T|  |ignored  \        | |
+  | |                `-'                | |T|  `---------'        | |
+  | |                 |                 | |T|                     | |
+  | |                 |                 | |T|----.                | |
+  | |                 |                 | |T|    | timeout        | |
+  | |                 |                 `-^-'<---'                | |
+  | |                 |     computed     |                        | |
+  | | <-----------------------------------------------------------| |
+  `-'                 |     position     |                        `-'
+,--+---.          ,---+----.        ,----+-----.             ,-----+----.
+|Client|          |Listener|        |Aggregator|             |Positioner|
+`------'          `--------'        `----------'             `----------'
+```
+
+The PlantUML source file for this figure is provided along with the
+OwlPS distribution, in the ``doc/figures/`` directory.
+
+
+
+
 = Files =
 
 : //{{INSTALL_PREFIX}}/etc/owlps/owlps-aggregator.conf//