The rootallchildall setting causes all entity declarations to be written in the root document's subset, and in the subset of all its children. This produces valid SGML in that the root document contains declarations for all entities of the document tree, and additionally writes all entity declarations in a special comment subset at the front of file entities. That can be useful if the file entities are edited standalone (that is, edited directly instead of being edited by being opened from the parent document) and if access to all the entities declared in the entire document tree is necessary during this standalone editing. With this setting, if an entity declaration is present in one file entity's subset, every file of that document tree that is saved will include the entity declaration.

The main drawback of this method is the larger size of fragments both when stored, and in memory. Another drawback is slower performance when performing operations such as deleting entity declarations.

While this setting most closely approximates pre-8.0 behavior, these drawbacks generally make it undesirable for sites where large documents are published of many file entities or objects.