Question

Assallam aylikum:

I must say alhamdilliah for this wonderful website. May Allah accept all of
your duas.

Correct me if I am wrong the  ORGINAL madd (ASLI) if it comes at the end of
any ayat with a letter next to it will be called presented sukkon. The leen
tends to act this way. So would the LEEN be called a natural madd? 

Answer

Wa alaikum assalaam wa rahmatu Allahi wa barakatuh.

Jazakum Allahu khairan, and may Allah accept all your duas also. 

If there is a medd letter, or original medd in a word, and there follows after the medd letter only one letter and this letter is voweled, when stopping on this word (it does not have to be at the end of an aayah), the lengthening (medd) then becomes a presented sukoon lengthening ()  that can be lengthened 2, 4, or 6 counts.  An example would be when stopping on the word: .

The medd al-leen is when there is a leen letter, which is a  or  saakinah preceded by a fat-h and followed by one letter only, and that letter is voweled and we are stopping on it with a presented sukoon.  This medd is also lengthened 2, 4, or 6 vowel counts.  Examples of this would be when stopping on or .  The presented sukoon medd and the medd al-leen are not the same, and there is a relationship that must be kept when reciting.  A leen medd must be equal or less than the presented sukoon lengthening () in our recitation.
 The leen letter which is a   or  saakinah (not voweled) preceded by a fat-h, but either we are not stopping on the word, or there is more than one letter after it or no letter after it, is not a natural (original) medd, and its lengthening is less than the two counts of the natural (original) medd, but more than one vowel count.  An example of the leen letter is: .  The lengthening of the leen letter (not the medd al-leen) is called , which means "some lengthening".