I plead (semi) guilty here. Despite the fact that I don't have a deep understanding of DSA, I wrote the Terminology section as an attempt to distill notions from the mini-tutorial from the forum, the LuCI web GUI, etc. I also found a DSA "spec" on the wider internet that didn't seem to contain any definitions at all.
That's why I put the disclaimer on the page: This page is a Work In Process. It contains requests for information from future editors. If you can contribute your knowledge, we would be pleased for the help.
To address your specific question, it's my sense that those are OpenWrt conventions.
That said, I am completely prepared to stand aside if anyone who knows more than I wants to update the wiki page. Thanks.