1st character:
C = Container
F = Folder
M = Multiple
L = Leaf
O = Modifier container
D = Modifier folder
R = Modifier leaf
2nd character:
A = Active
I = Inactive
H = Hidden
3rd character:
E = Editable
Containers and folders are the yellow rectangles with plus signs next to them that can be expanded to display other folders or leaves.
Concept folders (
) and containers ( 
) have a magnifying glass in the icon.Modifier folders (
) and containers ( 
) have a blue bulls eye in the icon.
The difference between a container and a folder is that a container cannot be dragged into a panel in the workbench as a query item, while a folder can be a query item. i2b2 primarily uses folders, which means that most terms can be used in queries.
Leaves are the lowest level of a hierarchy. They cannot be expanded any further.
Concept leaves (
) are depicted by a grey rectangle with a magnifying glass. Concept leaves ( 
) are depicted by a blue bulls eye.
Multiples are terms where there is more than one term mapped to an item, but only one is displayed.
An example is under Gender in the Demographics folder, the term "Unknown" has a black dot in the magnifying glass indicating that there are at least two terms that are considered to be "Unknown Gender" and both are mapped to this one.
The second character of _C_VISUALATTRIBUTES_ describes the status of the term.
An active term is displayed normally.
An inactive term is greyed out; it appears in the client to let the user know it is there but it cannot be used.
A hidden term is just that – it is hidden from the user entirely.
The third character of _C_VISUALATTRIBUTES_ indicates that the term can be edited. If a term is a folder or container then a child term can be added to it. Editable terms may also be deleted.