Use of parent_id?

[Erik Hommel]

Hi all, in the table civicrm_campaign there is a field called parent_id. At the moment I can not see any use is being made of this field. For a project we are developing a prototype of a relationship between campaigns (to reflect projects and programs), and we could certainly use this field in the extension we are going to develop. However, I want to make sure there are no ongoing core developments that are planning to use this field for something entirely different.
To be on the safe side I will start with our own table civicrm_campaign_parent.....

[Eileen]

Erik - it would be good to get an answer on this & on activity.parent_id & update the comments in the xml for those fields. My suspicion is that neither are in current use - or not in any way that would prevent you using them & that using the core ones makes sense