SuttaCentral
There are small icons at the top of the suttas, for instance:
as shown in the image below, they include a small bookmark icon… but what do they mean? (Incidentally, it’s cool that they are ultimately implemented as SVGs!)
Thanks friends
— your local insomniac.
These are “book” icons, they indicate that the relevant info is the volume/page reference for printed edition.
facepalm Now I see that it is a book with a bookmark. Thanks!
If you hover over it, you will see exactly what it means:
Unfortunately hover doesn’t work on mobile. And it’s only the text, not the icon, that gives the hover text.
How I did not notice that I do not know! Thanks!
…also… there are TWO editions by the PTS. Learn something every day.
Yes, in certain cases only. Mostly there’s just one, but in a couple of cases the first edition was not done well and it was corrected later. Unfortunately references in such cases may be to either edition.
I don’t know if it’s the site or my machine, but even knowing there was hover text, it felt like it took a while to pop up.
If I’m not mistaken, moving forward the plan is to have the site more geared towards mobile, so hover doesn’t even work. But if it is still being designed for desktop, I would suggest adding the hover text to the icon as well. If it’s easy.
It’s actually broken on the new site, so I’ll review the UI when fixing it. As a rule, it’s usually best to avoid putting information in tooltips.
Then huzzah! This little question has helped in a tiny way. 
I’ve personally become a big fan of <details><summary> You can style the summary and expanded details however you like, and you get click-based open/close for free (no js) across browsers and mobile and the html is semantically correct / meaningful.
Yeah, me too, we use them a lot actually. On the staging site we have them for the share button on the suttaplexes, for info on text views, for showing extra editorial info, etc.
In this specific case, though, I think there’s enough room to just show the two sources.