Building a list field equivalent

[TonyM]

Folks,

I am look for a little direction on this if possible.

• I am working on a "Tree maker" and are aware of Mario's New Here with parent, and the alt-tags plugin. 
• I want to create trees with a field other than tags, and children can simply name their parent in a treename-tree field.
• However I am keen to emulate the list field in which the order of the children can be listed, perhaps a treename-list field
• As you may be aware there are various conditions in which the list field is automatically generated such as when changing order using a tagpill
• Then this is updated in other conditions?

Can anyone share the logic behind how the list field is implemented, especially when there is no list field yet, and when it should be created?

Thanks in advance

Tony