--- title: "Key concepts - Data Center" canonical: "https://support.appfire.com/space/CSOT/68749794/Key%20concepts%20-%20Data%20Center" format: markdown --- > Macro (aura-html) This section explains key concepts of the app such as workflow post functions, issue fields, as well as when to use Original vs. Parent values. ## Workflow post function --- As a Jira administrator, one of the aspects of a workflow that you can control is post functions. The primary purpose of a post function is to carry out additional processing that may be required after a workflow transition has been executed. Examples include: - creating a change history record for the issue - adding a comment to an issue - updating an issue's field - creating an event to trigger one or more email notifications Jira has both [essential](https://confluence.atlassian.com/adminjiracloud/advanced-workflow-configuration-776636620.html#Advancedworkflowconfiguration-essentialpostfunctionsEssentialpostfunctions) and [optional](https://confluence.atlassian.com/adminjiracloud/advanced-workflow-configuration-776636620.html#Advancedworkflowconfiguration-optionalpostfunctionsOptionalpostfunctions) post functions and it is important that you understand their differences as they pertain to the introduction of new post functions with Create on Transition. ## Issue fields --- Create Issue and Create Sub-task post functions support quite a number of fields (Issue fields) that can be configured to help you control both: - when the issue should be created and - what information is associated with the issue once created Many of our customers have found it helpful to [review each issue field](https://appfire.atlassian.net/wiki/spaces/CSOT/pages/68752325) and capability ahead of creating their first post function. ## Original vs. parent Values --- **Original Issue** - The original issue that started the workflow transition. This could be an issue or sub-task.