Databases in Correspondence

So I was having a discussion with a friend and he told me that using databases during correspondence chess is cheating. I know on another site you can use a database but what about on here?

You can use the lichess database. It's built in to the analysis board (it's the little book icon.)

Thank you. What about other databases please? As long as they don’t include engine analysis?

#3 Related post from a month ago by mods...

From somethingpretentious
lichess.org/forum/lichess-feedback/can-we-please-clarify-the-rules-regarding-the-use-of-books-in-correspondence-chess?page=2#20
"We're currently working on a new version of the terms of service though and will include clarification on this point."

From FlamoToolz
lichess.org/forum/lichess-feedback/can-we-please-clarify-the-rules-regarding-the-use-of-books-in-correspondence-chess?page=4#35
"My apologies-- opening books outside of lichess ARE allowed"

I don't think you can use databases - like Mega Database - other than the Lichess opening book.

OK cuz I got an app on my phone called Opening Tree so wanted to know if that was allowed

It is allowed- as long as it doesn't have an engine. (which from using browser version it doesn't have an engine)

Thank you everyone

Besides the legalese, using your judgment and assuming fair intentions, look at the limits of the current lichess on site features for correspondence, you could realize that there is a cutoff for game lengths.

The in-game opening explorer is not showing the same depth as the one directly accessible from lichess main page.

I don't know the exact cut-off criterion. if it is a fixed depth. or some upstream ply distance from outcome... I know the is a max ply involved, but then some games might already be shorter. These type of detail I think can be induced or deduced (depending on your coding knowledge) from the issues on github, going back in the history (looking for max and ply, maybe one word).