Backbone has multiple options for synchronizing version fields.
Same version to same version
If you want to synchronize all issues to the same version in both instances, simply select the Passthrough Field Value Mapping option.
If one synchronization partner tries to synchronize a version with an instance without a version with the same name, the synchronization won't work. To avoid this, select Create missing versions to automatically create a version with the same name in the partner instance when the synchronization is initialized.
Specific version to specific version
You can synchronize specific versions to other specific versions (for example, you can synchronize issues in version '1' in Project A to version 'one' in Project B).
To do so, select the Versions Field Value Mapping setting, and in the Version mapping section, click Add Entry to enter the versions you want to synchronize. The versions are mapped according to the number they are assigned to – so the version assigned to number 1 on the left side will be synchronized to version 1 on the right side.
You must also select a default version for the issue to be mapped to in case you are synchronizing a version that you haven't created a mapping for. You can do this using the Default Version dropdown.
Synchronize version (and version information) to a free text field
You can synchronize a version, and placeholders displaying information about that version, to a free text field. The mapping can only be unidirectional, because Backbone doesn't support parsing the version field from the other instance.
In the version mapping configuration, select the Versions Passthrough Mapping option for the sending project, and then in the receiving project, enter a custom text string. The following placeholders are available:
|the version's JIRA id|
|the version's JIRA self URL|
|the version's JIRA display name|
|the version's JIRA description|
|the release date defined for this version|
|displays 'true' if released, 'false' otherwise|
|displays 'true' if archived, 'false' otherwise|
Only synchronize versions with a certain name structure
You can choose to only synchronize versions with a certain name structure. To do so, select the Passthrough Field Value Mapping option, and specify the name structure of versions to be synchronized by entering a regex in the Allowed Version Pattern box.