One of my favourite acronyms from the world of computing and technology is XINU. It stands for 'XINU Is Not Unix'. The delightful thing about this acronym is that XINU is also UNIX spelled backwards.

For a given word W, a recursive acronym that both negates W and reverses it is possible when W has the form W = '?NI?' where each '?' denotes a letter. Some fictitious examples make this clearer:

- LINA Is Not ANIL.
- TINK Is Not KNIT.
- OINO Is Not ONIO.

Words of the form '?N?' also work if we are happy to contract the word 'is' in the acronym. In fact, in this case we can even obtain circular recursive acronyms:

- ANI's Not INA. INA's Not ANI.
- ONE's Not ENO. ENO's Not ONE.

In each pair, the two acronyms negate each other, making them circular while also being reverses of one another. Such acronyms could serve as amusing names for expressing friendly banter between rival projects.

Further, if we make the acronyms refer to themselves, we get paradoxes too:

- ANA's Not ANA
- XNX's Not XNX