Just a simple recommendation, I don't like the abbreviations anyway, could there be a table on hover, e.g *:

![Preview](https://i.sstatic.net/qkcyL.png)

<sub>* Like the [Roomba Forecaster](https://stackapps.com/questions/7239/roomba-forecaster-when-will-the-question-be-roombaed-if-it-wont-why)  userscript.</sub>

The table can contain long details like "Answered the question", "Edited the question", etc.