what is the lowest amount i can transfer using bitcoin ? can i send 0 satoshis? i was looking at this bitcoin tx

https://blockchain.info/tx/b4ea693a9d2d7e32b66777964fce13da302bed024bd9fd4651919da650fb1c40

where

Inputs and Outputs
Total Input 0.00003 BTC
Total Output    0 BTC
Fees    0.00003 BTC
Fee per byte    12.821 sat/B
Fee per weight unit 3.205 sat/WU
Estimated BTC Transacted    0 BTC


the user has set total output as 0 BTC so in short all input is given as fee.

Is this common practice or bug ?
This is unexpected (but valid) behavoiur of mining pool software. btw, i am creator of this tx