A NOT gate switches the state of the input. So if the input is TRUE then the output will be FALSE and vice versa.

Input	Output
Input 0	Output 1
Input 1	Output 0

The simplest logic requirement that Reskillable supports is the ability to invert a requirement. It does this using a NOT gate and the syntax for it is not|requirement. As described above in the section about Logic Gates, this logic requirement will only be marked as met if the specified requirement is not met.