Each Member on the first level of your Unilevel Team counts as a "Leg". This means that placement can affect the number of legs you have. If you enroll 5 people, and place them one under the other, you will end up with only one Leg, since now only one of those 5 members will be on your first level, in terms of placement.
For a Leg to count as a qualifying Leg for Diamond, Green Diamond, etc. Structure Requirements, that Leg must contain at least one Member of the required Rank.
For instance, to Rank as Diamond, you are required to have three Consultant Legs. That means that you need at least 3 Members, who are on your first level (in terms of Placement), and each must have at least a Consultant ranked Member somewhere within their eight level downline. They will also count as Consultant Legs if they, themselves, qualify as Consultants.