Safety: "Safety" level is given to those individuals or objects that can be accommodated effectively and reliably. Security projects may require unique containment measures, but these measures will not fail frequently or need to be revised after more information is obtained from the project.

Some security level items are human, humanoid and/or perceptual. In order to prevent injuries and/or deaths of personnel and SCPs, communication with these SCPs must be professional and polite, and special accommodation measures should be considered.

It should be noted that safety classification does not mean that containment measures are not needed. Many safety-level projects can be very dangerous in some cases. The important difference between safety level and other levels is that these projects can run safely with appropriate measures. An example of a security category can be a gun, a nuclear weapon or polonium.

Euclid: The behavior of a project will be edited into Euclid when it cannot be predicted correctly, either because the project is perceptual and its behavior is beyond the current scientific knowledge or because the current understanding is limited. Euclid-level projects will not be as dangerous to human beings as Kurt-level projects when they break through shelters, but they need more attention than security-level projects.

Although many Euclid-level projects can be used to benefit the foundation and mankind, there may be unforeseen accidents after use because they are not well understood. Some Euclidean-level projects will be classified as safe after full understanding, but most of them are still mysterious after rigorous testing.

Keter-class "Keter" project not only shows strong and positive hostility to human life, civilization and/or four-dimensional space, but also has the ability to cause great damage when containment fails. These projects must be classified, adapted according to special adaptation measures and destroyed if possible. Just being enemies with human beings will not be classified as Keter R. A Keter-level project not only has the ability to cause devastating damage to human life and civilization, but also its acceptance agreement must be huge, complex and accurate in order to prevent it from doing so. It has always been a priority goal of the foundation to study how to destroy the special projects.

Division-level projects under the supervision of the Foundation are rarely destroyed by Foundation personnel, mainly because of the following three reasons: some projects are difficult to be destroyed because of invulnerability or similar circumstances, some projects are retained because of their great tactical value to the Foundation, and some projects are permanently taken in if they are destroyed, which may cause greater harm to mankind.

The Foundation has controlled some SCPs of Kurt level, but this situation is very rare: for example, SCP-076-2 will work for the Foundation just because of his unusual relationship with agents, and it has the ability to communicate with us, but even this did not last long. Most subjects are unconscious, and most of them are still life. This situation may change after more research and discovery.

Keter means "crown" in Hebrew, and it is the top source of Jewish mysticism.

Secondary classification

Abnormal: any project evaluated by the foundation for further research and special reception. Some of these items are catalogued in the abnormal item record. Note: SCPs without numbers are classified as anonymous, but some SCP items are classified as anonymous before being given SCP numbers.

Neutralization: anything that is destroyed or loses its characteristics, extra dimensions or negative effects. Items under this level should have a memo to record the previous information of the item.

Retirement: used for projects not only destroyed by the foundation, but also denied by the foundation.

Confidential classification

Thaumiel:Thaumiel level is an extremely confidential and rare anomaly, which is used by the foundation to control or offset other extremely dangerous anomalies, especially Keter level projects. The existence of the Thaumiel-level project itself belongs to the top secret of the Foundation, and its location, function and current situation are only known by O5 Members and a few Foundation personnel.