Nothing in particular, just what the OP decided to use. Start a topic and see what icons you can use, then press escape if you don't want to continue with that topic.
Next to the category headings on the main page is a green or blue icon, depending on whether there is new content or not. Until recently I wondered why PC had chosen a jug kettle as that icon. Closer inspection reveals it to be a file divider with tab: makes sense now :silly: :silly:
Mel