It's different from C language, WhenDo is more like parallel execution coding. After you followed the beautiful booklet of WhenDo Programming, you could get a clue how it works. Hope it makes sense. (sorry for my poor English, feel hard to explain it clearly.)
Thanks for the reply! So, I saw in the booklet, but I don't see what the difference is between the two symbols. Is there a difference? In the book I can't see a difference in their use, or how to get one symbol vs the other.