WebCrypto spec: typographic conventions ?

wrt https://dvcs.w3.org/hg/webcrypto-api/raw-file/tip/spec/Overview.html

In perusing the above-linked webcrypto spec editors' draft perhaps I'm just not getting it, but I'm  finding it difficult to understand the employed typographic conventions.  Perhaps part of this is because I am unable to find a section thoroughly describing typographic conventions.  S 9 Termin