Members are a type of tag that is part of what is known as an Axis. There are Axes and Members within the taxonomy as illustrated below.
Sometimes, it is necessary to create a custom axis or member.This can be done by selecting the relevant column in the Table tagging view and then clicking the Add Dimension Member button.
This will bring up the dialogue for Custom Members and Axes. You can ignore the top 3 drop down menus in my understanding. To create a new Member, click on Create. If you wish to create a new Axis, you must also tick the Extend box and fill in an Axis and an Axis name.
The Axis name is the technical name and should be written in CamelCase. When creating a new Custom Axis, make sure to create the default Member for the first one as you can get errors if a Custom Axis does not have a default Member. This is done by ticking the Default box.
In the Member Label you should write what you want the Member to be called. Member Name is the technical name and should be written in CamelCase. Then click save and Apply to tag the previously selected cells with this new member.