A couple key things to note here is that importing structure to PDMLink works a little bit different between versions and is not documented.
In 8.0 you could load Parent/Child relationships from the top-down if you had several structures that needed to be loaded. In 9.1 this behavior is changed and you can only load Parent/Child structures using a bottom up technique. These are subtle differences that the guide is lacking in detail. However if you plan to load a full structure with the detail of level 1-7 etc... specified in the file you should be OK. Just depends on the amount of data to load and the number of structures. In our case loading parent/child structures significantly reduced the number of items to load and increased the efficiency of this process.
