Negation
The negation operand can be understood based on common language use: it corresponds to the word “NOT”.
Figure: Graphical representation of a negation
- 1
- Address space to which the negation applies
- 2
- The negation excludes a subset
Example
~1.2.3.4 (negation of IP address 1.2.3.4) includes all other possible (IPv4) addresses except the IP address 1.2.3.4. As you see, negations are a good way to create a simple element that includes large IP address spaces with some exceptions. Usually, the negation appears in constructions like the following: 192.168.10.0/24 ⋂ ~192.168.10.200. This example basically means “include all addresses in network 192.168.10.0/24, but do not include address 192.168.10.200”.This definition uses the intersection operand, which is explained next. We return to this same example to explain the intersection part of the equation. Also, the section explaining the union operand returns to this example once more to explain why a union operand is not appropriate here.