Hierarchical gating: As mentioned on the linking pages, most software packages apply gates to flow cytometry data in a hierarchical fashion. A graphic of this approach generated using Flowjo illustrates a gating hierarchy, with each gate nested within the parent gate.

This approach means that each region which is drawn is defined with an inclusive AND logic. Therefore in the above example, in order to be classified as CD56+, an event must initially fall within the "Viable" gate, (AND) the Ly5a positive gate. This approach to gating is often all that is needed by many users, however other users wishing to have more flexibility in their analysis are often more satisfied with gating approaches which allow changes in gates logic. For example with the above gates, if one can change the logic to a combination of AND and OR logic, one can view cells which meet the Viable gate, and are either Ly5a positive OR negative, without the need to draw additional gates.

Gates which are defined by other approaches are not currently dealt with on this page.