Page History

...

ContentAssoc relates one Content entity to another. A sense of direction is conveyed in the fact that one field is named contentIdTo (the from field is contentId).

contentIdcontentIdTo
This is the 'parent' Content in a Content-to-Content relationship.

contentIdTocontentId
This field is the 'from' or 'child' field in a Content-to-Content relationship.

...