The following attributes are extension attributes for the camunda namespace http://camunda.org/schema/1.0/bpmn.

connector

Description
The configuration of a camunda connector.
Attributes
——-
–
Constraints
——-
The camunda:connectorId child element is required and must identify a connector implementation known to the process engine
Parent elements
——-
Service Task, Business Rule Task, Send Task, Message Event Definition of Message Intermediate Throwing Event or Message End Event,
Child elements
——-
camunda:inputOutput, camunda:connectorId

connectorId

Description
The unique identifier of the connector type to instantiate.
Attributes
——-
–
Constraints
——-
The connector type has to be known to the process engine
Parent elements
——-
camunda:connector
Child elements
——-
–

constraint

Description
Metadata of an individual validation constraint for a form field (see Form Field Validation).
Attributes
——-
name The name of the form field constraint type
config The configuration of the form field constraint type
Constraints
——-
The name attribute must be one of the known validators (required, minlength, maxlength, min, max, readonly or validator)
Parent elements
——-
camunda:validation
Child elements
——-
–

entry

Description
A single entry of a map structure. The value can be a constant, expression, script, list or another map.
Attributes
——-
key The key of the entry in the map. Can be a string or an expression.
Constraints
——-
The key attribute is required
Parent elements
——-
camunda:map
Child elements
——-
camunda:list, camunda:map, camunda:script

executionListener

Description
Add an execution listener to an event.
Attributes
——-
event The type of the event for which the listener is called
class see camunda:class
expression see camunda:expression
delegateExpression see camunda:delegateExpression
Constraints
——-
The event attribute is required (except for transitions) and must be one of the task events: start or end
One of the attributes class, expression or delegateExpression is mandatory
Parent elements
——-
Process, Task, Service Task, Send Task, User Task, Business Rule Task, Script Task, Receive Task, Manual Task, Exclusive Gateway, Sequence Flow, Parallel Gateway, Inclusive Gateway, Event Based Gateway, Start Event, Intermediate Catch Event, Intermediate Throw Event, End Events, Boundary Events, Embedded Subprocess, Call Activity, Event Subprocess, Transaction Subprocess
Child elements
——-
camunda:field, camunda:script

expression

Description
Defines an expression to inject in delegated classes (see Field Injection).
Attributes
——-
–
Text Content
——-
The expression to inject
Constraints
——-
–
Parent elements
——-
camunda:field
Child elements
——-
–

failedJobRetryTimeCycle

Description
Defines the custom retry schedule for a failed job (see Failed Jobs).
Attributes
——-
–
Text Content
——-
The retry time cycle value or expression
Constraints
——-
The configuration follows the ISO 8601 standard for repeating time intervals
Parent elements
——-
Task, Service Task, Send Task, User Task, Business Rule Task, Script Task, Receive Task, Timer Start Event, Timer Intermediate Catching Event, Timer Boundary Event, Intermediate Signal Throw Event, Embedded Subprocess, Call Activity, Transaction Subprocess, Multi Instance Loop Characteristics
Child elements
——-
–

field

Description
Defines the value to inject in delegated classes (see Field Injection).
Attributes
——-
name The name of the field
expression The value of the field as expression
stringValue The value of the field as String
Constraints
——-
Only one attribute of stringValue and expression or one of the child elements string and expression can be used
Parent elements
——-
Service Task, Business Rule Task, Send Task, Message Event Definition of Message Intermediate Throwing Event or Message End Event, camunda:taskListener, camunda:executionListner
Child elements
——-
camunda:expression, camunda:string

formData

Description
Metadata to define fields of a form, which are used to generate task forms (see Generated Task Forms).
Attributes
——-
–
Constraints
——-
–
Parent elements
——-
Start Event, User Task
Child elements
——-
camunda:formField

formField

Description
Metadata to define a single form field (see Generated Task Forms).
Attributes
——-
id The id of the form field, corresponding to the name of a process variable
label The label to be displayed next to the form field
type The type of the form field
datePattern The pattern of a date type form field
defaultValue The value to be used as a default (pre-selection) for the field
Constraints
——-
The attribute id may not be empty
The attribute type can be one of the known form field types (string, long, boolean, date or enum) or a custom one
The attribute datePattern can only be used if the type attribute is set to date
The child element camunda:properties is only allowed once
The child element camunda:validation is only allowed once
The child elements camunda:values can only be used if the type attribute is set to enum
Parent elements
——-
camunda:formData
Child elements
——-
camunda:properties, camunda:validation, camunda:value

formProperty

Description
Metadata to define a form field (Deprecated, use camunda:formData).
Attributes
——-
id The key used to submit the property through the API
name The display label of the property
type The type of the property
required True if the form field is required (default: false)
readable True if the form field is readable and will be displayed (default: true)
writeable True if the form field is writeable (default: true)
variable Specifies the process variable on which the variable is mapped
expression Specifies an expression that maps the property, e.g., ${street.address}
datePattern The pattern of a date type form field
default The default value or expression of the property
Constraints
——-
The id attribute is required
The attribute type can be one of the known types (string, long, boolean, date or enum) or a custom one
The attribute datePattern can only be used if the type attribute is set to date
The child elements camunda:values can only be used if the type attribute is set to enum
Parent elements
——-
Start Event, User Task
Child elements
——-
camunda:value

in

Description
The element specifies variables which should be passed to the subprocess, see passing variables for more information.
Attributes
——-
source A name of a process variable to be passed in
sourceExpression An expression to be evaluated and passed in
variables Can be set to all to pass all process variables in
target Name of the process variable inside the subprocess instance
local Can be set to true to only pass local variables of the execution that executes the call activity.
businessKey Set the business key of the subprocess process instance
Constraints
——-
Only one of the attributes source, sourceExpression, variables or businessKey can be used
The attribute target is required if the source or sourceExpression attribute is used
Parent elements
——-
Call Activity, Signal Events (in Intermediate and End Throwing Events)
Child elements
——-
–

inputParameter

Description
An single input mapping for the activity. If the element has no child element, the text content of this element is mapped into the activity. The text content can be a constant string value or an expression. If no child element or text content exists, the variable inside the activity is set to the special value null.
Attributes
——-
name The name of the variable inside the activity.
Constraints
——-
The name attribute is required.
The element can have one child element, a constant string or an expression as text content.
Parent elements
——-
camunda:inputOutput
Child elements
——-
camunda:list, camunda:map, camunda:script

inputOutput

Description
The element describes an input/output mapping for the activity.
Attributes
——-
–
Constraints
——-
–
Parent elements
——-
All Tasks, All Events (except Start and Boundary Events), Call Activity, Embedded Subprocess, Transaction Subprocess, camunda:connector
Child elements
——-
camunda:inputParameter, camunda:outputParameter

list

Description
A list structure. If the list contains multiple values, they should be added as text content of child elements. Which child elements are used is arbitrary, e.g.,: 
  1.     <camunda:list>
  2.       <camunda:value>one</camunda:value>
  3.       <camunda:value>two</camunda:value>
  4.       <camunda:value>three</camunda:value>
  5.     </camunda:list>
  6.   </code> A [ camunda:script](https://docs.camunda.org/manual/7.9/reference/bpmn20/custom-extensions/extension-elements/#script) element can also be used as a list element. The return value of the script is added to the list. Furthermore, lists can contain nested lists and maps.
Attributes
–
Constraints
——-
Multiple values have to be encapsulated in child elements.
Parent elements
——-
camunda:inputParameter, camunda:outputParameter, camunda:list, camunda:entry
Child elements
——-
Any child element, camunda:list, camunda:map

map

Description
A map structure. The entries can be constants, expressions, scripts, nested maps and lists.
Attributes
——-
–
Constraints
——-
–
Parent elements
——-
camunda:inputParameter, camunda:outputParameter, camunda:list, camunda:entry
Child elements
——-
camunda:entry

out

Description
The element specifies variables which should be passed back from the subprocess, see passing variables for more information.
Attributes
——-
source A name of a process variable to be passed back
sourceExpression An expression to be evaluated and passed back
variables Can be set to all to pass all subprocess variables back
target Name of the process variable inside the subprocess instance
local Can be set to true to pass variables from the called case/process instance to local variables of the execution executing the call activity.
Constraints
——-
Only one of the attributes source, sourceExpression or variables can be used
The attribute target is required if the source or sourceExpression attribute is used
Parent elements
——-
Call Activity
Child elements
——-
–

outputParameter

Description
An single output mapping for the activity. If the element has no child element, the text content of this element is mapped out of the activity. The text content can be a constant string value or an expression. If no child element or text content exists, the variable outside of the activity is set to the special value null.
Attributes
——-
name The name of the variable outside of the activity.
Constraints
——-
The name attribute is required.
The element can have one child element, a constant string or an expression as text content.
Parent elements
——-
camunda:inputOutput
Child elements
——-
camunda:list, camunda:map, camunda:script

potentialStarter

Description
Defines which users or groups can start the process.
Attributes
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–
Constraints
——-
–
Parent elements
——-
Process
Child elements
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resourceAssignmentExpression

properties

Description
A key value list of properties which be can be interpreted freely.
Attributes
——-
–
Constraints
——-
–
Parent elements
——-
Base Element, camunda:formField
Child elements
——-
camunda:property

property

Description
A key value pair which can be interpreted freely.
Attributes
——-
id The id of the form field property
name The name of the property
value The value of the property
Constraints
——-
If the property belongs to a camunda:formField extension element, only the attributes id and value are used.
If the parent camunda:properties element is directly added as an extension element, for example by the camunda Modeler, only the attributes name and value are used.
Parent elements
——-
camunda:properties
Child elements
——-
–

script

Description
A script element. The script is executed and the return value is used as mapping value.
Attributes
——-
scriptFormat The format identifier, normally the language of the script source code
resource equivalent to camunda:resource
Constraints
——-
The scriptFormat attribute is required
If the resource attribute is used, no source code text content is allowed
Parent elements
——-
camunda:inputParameter, camunda:outputParameter, camunda:entry, camunda:list, camunda:executionListener, camunda:taskListener
Child elements
——-
–

string

Description
Defines a String value to inject in delegated classes (see Field Injection).
Attributes
——-
–
Text Content
——-
The String value to inject
Constraints
——-
–
Parent elements
——-
camunda:field
Child elements
——-
–

taskListener

Description
Adds a task listener to a task event.
Attributes
——-
event The type of the event for which the listener is called
class see camunda:class
expression see camunda:expression
delegateExpression see camunda:delegateExpression
Constraints
——-
The event attribute is required and must be one of the task events: create, assignment, complete or delete
One of the attributes class, expression or delegateExpression is mandatory
Parent elements
——-
User Task
Child elements
——-
camunda:field, camunda:script

validation

Description
Metadata to define a list of validation constraints for form fields (see Form Field Validation).
Attributes
——-
–
Constraints
——-
–
Parent elements
——-
camunda:formField
Child elements
——-
camunda:constraint

value

Description
Possible values of a form field with the type enum.
Attributes
——-
id The id of the value
name The name of the value
Constraints
——-
–
Parent elements
——-
camunda:formField, camunda:formProperty
Child elements
——-
–

原文: https://docs.camunda.org/manual/7.9/reference/bpmn20/custom-extensions/extension-elements/