System Module

System.SynchronizationErrorFile

File attachment for offline synchronization errors. Extends System.FileDocument.

3. HTTP / Web Services

System.HttpMessage (base, non-persistent)

Base entity for HTTP messages. Not stored in the database.

System.HttpRequest (extends HttpMessage, non-persistent)

System.HttpResponse (extends HttpMessage, non-persistent)

System.HttpHeader (non-persistent)

Usage: These entities are used in published/consumed REST services and Java actions that handle HTTP requests and responses directly.

System.ConsumedODataConfiguration

Configuration for consumed OData services.

System.ODataResponse

4. Error Handling

System.Error (non-persistent)

System.SoapFault (extends Error, non-persistent)

SOAP-specific fault information. Extends System.Error with SOAP fault details.

System.SynchronizationError

Tracks offline mobile synchronization failures.

7. Utility Entities

System.Paging (non-persistent)

Paging information for data retrieval in custom Java actions.

System.UserReportInfo

Information for user management reports (internal use).

System.ProxyConfiguration

HTTP proxy settings (internal use).

8. Enumerations

Inspect any of these from the CLI rather than copying from here — the values are case-sensitive, and a wrong one is only caught at build time as CE1613 "The selected enumeration value no longer exists":

mxcli -p app.mpr describe enumeration System.WorkflowActivityType
mxcli -p app.mpr list enumerations            # includes the System module

Two of these names are easy to confuse, and mixing them up is the mistake that CE1613 usually reports: WorkflowActivityState has Finished, while WorkflowActivityExecutionState has Completed. They are different enumerations on different entities.

System enumerations are read-only — they are built into the platform, not stored in the project, so create/alter/drop/move enumeration System.… is refused. describe prints them as -- comment lines for that reason.

ContextType

System, User, Anonymous, ScheduledEvent

DeviceType

Phone, Tablet, Desktop

EventStatus

Running, Completed, Error, Stopped

ProxyConfiguration

UseAppSettings, Override, NoProxy

QueueTaskStatus

Idle, Running, Completed, Failed, Retrying, Aborted, Incompatible

UnreferencedFileState

New, Obsolete, Deleted

UserType

Internal, External

WorkflowActivityExecutionState

Created, InProgress, Completed, Paused, Aborted, Failed

WorkflowActivityState

Started, Suspended, Finished, Replaced, Aborted, Failed

WorkflowActivityType

Start, End, ExclusiveSplit, ParallelSplit, ParallelSplitBranchStopper, ParallelSplitMerge, UserTask, CallMicroflow, CallWorkflow, JumpTo, MultiInputUserTask, WaitForNotification, WaitForTimer, EndOfBoundaryEventPath, NonInterruptingTimerEvent, InterruptingTimerEvent

WorkflowCurrentActivityAction

DoNothing, JumpTo

WorkflowEventType

WorkflowCompleted, WorkflowInitiated, WorkflowRestarted, WorkflowFailed, WorkflowAborted, WorkflowPaused, WorkflowUnpaused, WorkflowRetried, WorkflowUpdated, WorkflowUpgraded, WorkflowConflicted, WorkflowResolved, WorkflowJumpToOptionApplied, StartEventExecuted, EndEventExecuted, DecisionExecuted, JumpExecuted, ParallelSplitExecuted, ParallelMergeExecuted, CallWorkflowStarted, CallWorkflowEnded, CallMicroflowStarted, CallMicroflowEnded, WaitForNotificationStarted, WaitForNotificationEnded, WaitForTimerStarted, WaitForTimerEnded, UserTaskStarted, MultiUserTaskOutcomeSelected, UserTaskEnded, NonInterruptingTimerEventExecuted, InterruptingTimerEventExecuted

WorkflowState

InProgress, Paused, Completed, Aborted, Incompatible, Failed

WorkflowUserTaskCompletionType

Single, Veto, Consensus, Majority, Threshold, Microflow

WorkflowUserTaskState

Created, InProgress, Completed, Paused, Aborted, Failed

9. Inheritance Hierarchies

System.User
  └── Administration.Account (adds FullName, Email, etc.)

System.FileDocument
  ├── System.Image
  └── System.SynchronizationErrorFile

System.HttpMessage (non-persistent)
  ├── System.HttpRequest
  └── System.HttpResponse

System.Error (non-persistent)
  └── System.SoapFault

Key point for MDL: When creating entities that store files or images, use extends:

mdl 1;
create persistent entity MyModule.Document extends System.FileDocument (
  title: string(200),
  version: integer default 1
);

create persistent entity MyModule.Photo extends System.Image (
  AltText: string(200)
);

10. Common Patterns

Audit Trail (CreatedBy / ModifiedBy)

mdl 1;
create association MyModule.Order_CreatedBy
from MyModule.Order to System.User
type reference;

create association MyModule.Order_ModifiedBy
from MyModule.Order to System.User
type reference;

File Attachments

mdl 1;
create persistent entity MyModule.Attachment extends System.FileDocument (
  description: string(500)
);

create association MyModule.Order_Attachments
from MyModule.Order to MyModule.Attachment
type ReferenceSet;

Workflow Context Object

mdl 1;
-- Application entity that serves as workflow context
create persistent entity MyModule.ExpenseReport (
  Amount: decimal,
  description: string(500),
  status: MyModule.ApprovalStatus default 'Draft'
);

-- Associate with workflow instance
create association MyModule.ExpenseReport_Workflow
from MyModule.ExpenseReport to System.Workflow
type reference;

Task Inbox Page

User tasks can be displayed in pages by retrieving System.WorkflowUserTask where the current user is in the target users or assignees.

XPath Tokens for System Entities

[%CurrentUser%]     -- The logged-in System.User
[%CurrentObject%]   -- The current context object

Source

This reference was extracted from the Java proxy files in javasource/system/proxies/ of a Mendix 10.x application. The System module domain model is not exposed in MPR/BSON files but is defined internally by the Mendix runtime. Proxy files serve as the definitive reference for available entities, attributes, and associations.