Celonis Process Modeler
Process Repository lets users design their process models according to the BPMN 2.0 standard
(1) you can use the standard BPMN 2.0 elements to model your processes
(2) by clicking on each process step you have two groups of possible actions. you can use "Append-to" options to connect the processing activity to another element such as a task, event, gateway, and etc. you can also change the type of the element.

By selecting the details section (3), users can define details of each process step by adding description, input/output, responsible role, and customer/supplier. such information will better help people to understand processes.

If process categories are assigned to a data model, the third section will be enabled for each process step, which is (4) Activities. this section provides a dropdown including activities as they are defined on the data model. modeling the process model using these activities is a requirement for doing conformance checking.
