I can read how to use an ad-hoc subprocess

docs/components/modeler/bpmn/ad-hoc/ad-hoc.md

@@ -0,0 +1,75 @@
+---
+id: ad-hoc
+title: "Ad-hoc"
+description: "The ad-hoc marker is only available for embedded subprocesses, allowing more flexibility while executing inner elements."
+---
+
+The ad-hoc marker (represented by a **~** tilde character) is only available
+for [embedded subprocesses](../embedded-subprocesses/embedded-subprocesses.md), and are therefore called **ad-hoc subprocesses**.
+Compared to regular subprocesses, ad-hoc subprocesses allow more flexibility for executing inner elements.
+
+![A demo process with an ad-hoc subprocess. Some elements inside the subprocess are active.](assets/ad-hoc-subprocess.png)
+
+The inner elements of an ad-hoc subprocess are not connected to a start or end event. Each element can be executed
+multiple times, in any order, or skipped.
+
+If elements depend on each other, the elements can be connected by a sequence flow to build a structured sequence
+within the ad-hoc subprocess.
+
+When a process instance reaches an ad-hoc subprocess, it [activates the inner elements](#activate-an-element) and waits
+for their completion. After the last element is completed, the process instance completes the ad-hoc subprocess and
+takes the outgoing sequence flows.
+
+### Constraints
+
+An ad-hoc subprocess has the following constraints:
+
+- Must have at least one activity
+- Must not have start events or end events
+- Any intermediate catch event must have an outgoing sequence flow
+
+## Activate an element
+
+An ad-hoc subprocess can define an expression `activeElementsCollection` that should return a
+[list](../../feel/language-guide/feel-data-types.md#list) of strings. Each string in the list should match to an ID of
+an inner element of the ad-hoc subprocess. Usually, the expression accesses a process instance variable that was
+created before and holds the list of element IDs.
+
+![A process with an ad-hoc subprocess that shows how a variable is used to active the inner elements.](assets/ad-hoc-subprocess-activation.png)
+
+When a process instance reaches an ad-hoc subprocess, it evaluates the expression `activeElementsCollection` and
+activates all elements whose element IDs are in the list.
+
+If the list is empty or the expression is not defined, no element is activated and the ad-hoc subprocess remains active.
+
+If the expression doesn't evaluate to a list of strings, or the list contains other values than inner element IDs, the
+process instance creates an incident.
+
+:::note
+Currently, it is not possible to activate elements dynamically after the ad-hoc subprocess is activated, only on
+entering the subprocess.
+:::
+
+## Variable mappings
+
+An ad-hoc subprocess can define input and output
+[variable mappings](../../../concepts/variables.md#inputoutput-variable-mappings).
+
+**Input variable mappings** are applied on activating the ad-hoc subprocess and before evaluating the expression
+`activeElementsCollection`. They can be used to create local variables for the ad-hoc subprocess.
+
+**Output variable mappings** are applied on completing the ad-hoc subprocess. They can be used to propagate local variables
+from the ad-hoc subprocess into the process instance. By default, no local variables are propagated.
+
+## Additional resources
+
+### XML representation
+
+```xml
+<bpmn:adHocSubProcess id="ad-hoc-subprocess" name="Ad-hoc subprocess">
+  <bpmn:extensionElements>
+    <zeebe:adHoc activeElementsCollection="=activeElements" />
+  </bpmn:extensionElements>
+  ... more contained elements ...
+</bpmn:adHocSubProcess>
+```

docs/components/modeler/bpmn/bpmn-coverage.md

@@ -122,6 +122,7 @@ import MultiInstanceParallelSvg from './assets/bpmn-symbols/multi-instance-paral
 import MultiInstanceSequentialSvg from './assets/bpmn-symbols/multi-instance-sequential.svg'
 import LoopSvg from './assets/bpmn-symbols/loop.svg'
 import CompensationSvg from './assets/bpmn-symbols/compensation.svg'
+import AdHocSvg from './assets/bpmn-symbols/ad-hoc.svg'
 
 <div className="bpmn-symbol-container">
     <a href="../multi-instance/">
@@ -136,6 +137,9 @@ import CompensationSvg from './assets/bpmn-symbols/compensation.svg'
     <a href="../compensation-handler/">
         <CompensationSvg className="implemented" />
     </a>
+    <a href="../ad-hoc/">
+        <AdHocSvg className="implemented" />
+    </a>
 </div>
 
 ## Data

docs/components/modeler/bpmn/markers.md

@@ -14,3 +14,4 @@ Currently supported markers:
 
 - [Multi-instance](multi-instance/multi-instance.md)
 - [Compensation](compensation-handler/compensation-handler.md)
+- [Ad-hoc](ad-hoc/ad-hoc.md)

sidebars.js

@@ -289,6 +289,7 @@ module.exports = {
                 "components/modeler/bpmn/markers",
                 "components/modeler/bpmn/multi-instance/multi-instance",
                 "components/modeler/bpmn/compensation-handler/compensation-handler",
+                "components/modeler/bpmn/ad-hoc/ad-hoc",
               ],
             },
           ],