The following is a description of the effects in the repository when moving or merging tags using the Tagging console:
When a tag A is moved or merged into tag B under /etc/tags:
tag A is not deleted and gets a cq:movedTo property.
tag B is created (in case of a move) and gets a cq:backlinks property.
cq:movedTo points to tag B. This property means that tag A has been moved or merged into tag B. Moving tag B will update this property accordingly. Tag A is thus hidden and is only kept in the repository to resolve tag IDs in content nodes pointing to tag A. The tag garbage collector removes tags like tag A once no more content nodes point to them. A special value for the cq:movedTo property is nirvana: it is applied when the tag is deleted but cannot be removed from the repository because there are subtags with a cq:movedTo that must be kept.
Note: The "cq:movedTo" property is only added to the moved or merged tag if either of these conditions are met: 1. Tag is used in content (meaning it has a reference) OR 2. Tag has children that have already been moved.
cq:backlinks keeps the references in the other direction, i.e. it keeps a list of all the tags that have been moved to or merged with tag B. This is mostly required to keep cq:movedTo properties up to date when tag B is moved/merged/deleted as well or when tag B is activated, in which case all its backlinks tags must be activated as well.
Note: The "cq:backlinks" property is only added to the moved or merged tag if either of these conditions are met: 1. Tag is used in content (meaning it has a reference) OR 2. Tag has children that have already been moved.