If you have a list where you have used indenting to group items, you may sometimes want to sort the indented items independently of their parent items. The way to do this is to Flatten the list by choosing Flatten Outline from the Tools menu. Flattening your list will remove all indentation from all items, allowing you to sort them as equals. A common example of this is a To Do list in which Priority numbers are assigned to indented items, which are grouped under parent items that represent different projects or tasks. You would sometimes like to just sort all the indented items by priority, so you can see the highest priority items together, independent of project or task.

When you Flatten your list, a new column is created called the Parent column. If you have more than one level of indentation in your list, a Parent column will be created for each level. These columns will usually be named Parent, Parent1, Parent2 and so on. The purpose of the Parent columns is to hold the information necessary for restoring the original hierarchy. For each item that was originally indented, the Parent column will hold the value of the Item column of its original parent item. Normally, you can just ignore the Parent columns.

Flattening your list does not simply produce a temporary flat view of your items. The list is actually changed to a flat list, with information about the original hierarchy stored in the new Parent columns. This means that there are no restrictions on the type of changes you can make to your list after it has been flattened. You can sort, rearrange items, edit their contents, delete items or add new ones. The only thing you need to keep in mind is that any changes to the values in the Parent columns, or to the Item columns of the original parent items, may affect the ability of ListPro to restore the original hierarchy of the list.

In most cases you will eventually want to restore the original hierarchy of the list. You can do this by choosing Unflatten Outline from the Tools menu. ListPro will then use the information in the Parent columns to restore the outline. Note that the changes you have made while the list was flattened may affect how the unflattened list actually looks. For example, if you have changed the order of the parent items, the unflattened list would reflect the new order. If you deleted items or changed the order of items that were indented under a common parent, the unflattened list would contain these changes, too.

It's also possible that you don't want to unflatten a list, but have decided you want to leave it flattened permanently. In that case, you can delete the Parent columns that were created when you flattened. Please be aware, however, that if you delete the Parent columns ListPro will not be able to unflatten the list.

Certain lists may not be possible to restore exactly after they have been flattened. For example, if any of the original parent items have a blank Item column, or if two or more of the original parent items have identical Item columns, the unflattening operation would not necessarily have enough information to restore the list exactly. ListPro will always warn you if this is the case before Flattening, however, so you can avoid flattening a list that can't be unflattened exactly.