Since the policy property must be enabled for synthetic backups, all clients that are included in the policy must support TIR.
See Collect true image restore information with move detection policy attribute.
The property indicates how long TIR information in the image catalog is kept before it is pruned (removed). The property is located in the master server host properties.
See About Keep true image restoration (TIR) information.
However, if a synthetic full and synthetic cumulative schedule was defined in the policy, the TIR information is pruned from the component images until a subsequent traditional or synthetic full or cumulative backup image has generated successfully.
Consider a situation where host specifies that TIR information is pruned from the catalog after two days. On the third day the TIR information is pruned only if a traditional or synthetic full backup image has been generated.
If the TIR information was pruned from a component image and you accidentally expire the most recent synthetic image, rerun the synthetic backup job to restore automatically the TIR information to the catalog. In case the TIR information cannot be restored due to bad, missing, or vaulted media, the synthetic backup job fails with error code 136 (TIR info was pruned from the image file). If the problem is correctable, run the synthetic backup again.
More Information
Recommendations for synthetic backups
Schedules that must appear in a policy for synthetic backups