I'm checking the minor vowel harmony in this site. It gives a good explanation about round vowels (regarding soft words )and the addition of suffixes starting with i. But would somebody enlightened me about the flat vowels as they were never discussed.
Another thing in my Turkish phrase book, "useful endings" like FROM is dan/tan for back vowel and den/ten for front vowel. But how do you know which one to use den or ten for front vowel same thing for dan/tan.

I hope i'm making sense.

thanks a lot

-den or -dan:

if the last SYLLABEL has: e,i,ö,ü then --> E > -den,-ten
if the last SYLLABEL has: a,ı,o,u then --> A > -dan,-tan

Ankara'dan
masadan
uzaktan
ağırdan
yukarıdan
eşekten
yürekten
yemekten

You must use –ten instead of –den, or –tan instead of –dan, when the word ends with a consonant of the words “fıstıkçı şahap”
Demek --> demekten
Sınıf --> sınıftan
kitap --> kitaptan

It’s explained here : http://www.turkishclass.com/grammar_consonantHarmony.htm
(case B- suffix mutation)