Marker Name and Position
Marker Name: This is what will display in the Annotation Marker dropdown list. Note that all your custom markers will appear in alphabetical order.
Marker Position: This is where the marker will display relative to where you click when you are placing an annotation. The small "x" shows where the click point is.
This makes it easier to place your annotations; for example, the existing Basic markers use the following settings:
Centered: Square, Dot