Wondering why with kilaab the diacritic "slash" is underneath the K and in the word kalaa3 the slash is above the K? Does it have something to do with the vowels? Also, not sure when the diacritic on the J of jubn is used (looks like a little oval with legs) is used instead of the slash?
I have read the Tips but I'm not very far along in the lessons so maybe have not come across them yet. The only ones I've seen mentioned is the forward slash to represent a short "a" and the upside down "w" to represent a doubling of the letter. Nothing has been mentioned about when or why to use the loop or why sometimes the slash is above a letter or below it. I'm not trying to be difficult - there just hasn't been any mention of it beyond "we'll talk about this later" type of message.
yes, above the letter مَ is a short a the mark is called "Fatḥah", below the letter مِ is a short i and the mark is called "Kasrah". i used a different letter (m instead of k) so it was a bit easier to see.
Short u is a little squiggle مُ called Ḍammah.
i suspect the squiggle for short u is based on و which can be a long u or "oo" (or w).
There's some info on duolingo if you use it through a browser [e.g. chrome] instead of the ap. Wikipedia also has quite a bit of info if you search any of those words or "arabic diacritics".