Issue Link Type
Issues link type defines the way issues will be linked by the field. This describes the relationship between the issues and what information is displayed on linked issues even without the linking field.
A JQL filter provides a powerful sorting possibility. Only issues matching the JQL filter will be displayed in the vLinks field. Existing Jira filter options can be used for this field. To ensure the JQL filter is built correctly, users have a green or red check mark that shows if the field is valid or not. Here are some examples and descriptions of their purposes.
Only issues with issue type 'story' can be linked to this issue
Only issues with issue type 'story' and the admin as 'assignee' can be linked to this issue
Only issues created before or after the current month can be linked to the issue
The view template defines what a user will see next to the linked issues key. The issue key is always displayed. It is built from the project key that it belongs to and the issue number. This key means that each issue is unique and can't be confused with other issues. Here are some examples of different template keys and the way they are displayed.
View Template: $assignee
The assignee is displayed next to the linked issue key
View Template: $summary
The summary is displayed next to the linked issue key