When editing annotations to accomodate a new set of shared parameters, you often just substitute an old parameter with its new version. This needs to be done by adding the new parameter, move it up to where its previous version was or is and then you continue to add prefixes, suffixes, line breaks and the occasional format adjustment. This idea is to allow to mark one parameter on the right and substitute it with one on the left. If the parameter on the right just marks a position for the new parameter to insert (as it would in schedules), we would need another symbol for the substituting feature.
