| CC | Description |
| C | This item has critical features such as tolerance, fit restrictions or application. Nuclear hardness properties have not been determined (not valid for input). |
| E | This item is a Flight Safety Critical Aircraft Part (FSCAP) and is specially designed to be or selected as being nuclear hard. |
| F | This item is a Flight Safety Critical Aircraft Part (FSCAP). |
| H | This item is specifically designed to be or selected as being nuclear hard (ie. it will continue to perform its designed function in an environment created by a nuclear explosion). This item does not have any other critical features. |
| M | This item is specifically designed to be or selected as being nuclear hard. In addition, this item has other critical features such as tolerance, fit restrictions or application. |
| N | This item does not have a critical feature such as tolerance, fit restrictions or application. Nuclear hardness properties have not been determined (not valid for input). |
| S | The item is a non-aviation Critical Safety Item (CSI) whose failure will result in serious damage to equipment or serious injury or death to personnel. |
| V | Item has not been reviewed for Flight Safety Critical Aircraft Part (FSACP), Critical Safety Item (CSI), or Critical Application Item (CAI) purposes by an approved engineering authority. |
| X | This item does not have a nuclear hardened feature or any other critical feature such as tolerance, fit restriction or application. |
| Y | This item does not have a nuclear hardened feature but does have other critical feature(s) such as tolerance, fit restriction or application. |