بنا بر بررسیهای پژوهشگران، ازجمله تئودور نولدکه، این حروف، مخفف نام افرادی است که نسخههای مختلف قرآن را در زمان عثمان از آن افراد جمعآوری کرده بودند. قرآن در زمان عثمان، خلیفهٔ سوم، تحت نظارت جمعی از صحابه به رهبری زید بن ثابت به صورت یک کتاب، موسوم به مصحف عثمان جمع گردید. بنا بر پژوهشهای محققان، حروف مقطعه نمایانگر حروفی بوده که به صورت برچسب بر روی جعبههای حاوی هر نسخه نوشته شده بود تا مشخص شود هر قسمت از متن از کدام شخص دریافت شده و بنابر این منظور از «الر»، الزبیر است و منظور از «المر»، المغیره و «حم» عبدالحمن است و طه کوتاهشده نام طلحه است که به عنوان برچسب بر روی جعبهها نوشته شده بود.
این ۷۸ حرف (که بدون تکرار ۱۴ تا میشود) به قرار زیر است:
و نیز با حذف حروف تکراری ۱۴ حرف باقی میماند:در عبارت (صراط علی حق نمسکه) جمع است
گفتنی است تفاسیر دیگری نیز دربارهٔ «حروف مقطعه»، از جانب قرآنپژوهان ارائه گشته و روایات زیادی نیز در اینباره نقل شدهاست. یک محقق مصری معتقد بود اگر حروف مقطعه در ابتدای هر سوره را به تفکیک بررسی کنیم، بیشترین حجم آن سوره متعلق به این حروف اند. به طور نمونه حروف الف و لام و میم که در ابتدای سوره بقره آمده است. با بررسی و شمارش تمام حروف این سوره این نتیجه حاصل میشود که حروف الف و لام و میم بیشتر از سایر حروف در سوره بقره بکار رفته است.اما در مورد اکثر سورههایی که با دیگر حروف شروع میشوند این موضوع صدق نمیکند مانند سورهٔ (طه) و سورههایی که با حروف مقطعه (طس) و (طسم) شروع شده است الف و لام و میم این سورهها بیشتر از حروف ط و س میباشند پس چنین استنباط میشود که موضوع به همین سادگیها هم نیست.
The Muqattaʿāt (Arabic: حروف مقطعات ḥurūf muqaṭṭaʿāt "disjoined letters" or "disconnected letters"; also "mysterious letters") are combinations of between one and five Arabic letters figuring at the beginning of 29 out of the 114 surahs (chapters) of the Quran just after the Bismillah. The letters are also known as fawātih (فواتح) or "openers" as they form the opening verse of their respective suras .
Muqatta'at occur in suras 2–3, 7, 10–15, 19–20, 26–32, 36, 38, 40–46, 50 and 68. The letters are written together like a word, but each letter is pronounced separately.
There are 14 unique combinations; the most frequent are ʾAlif Lām Mīm and Ḥāʾ Mīm, occurring six times each. Of the 28 letters of the Arabic alphabet, exactly one half appear as muqatta'at, either singly or in combinations of two, three, four or five letters. The fourteen letters are: ʾalif أ, hā هـ, ḥā ح, ṭā ط, yā ي, kāf ك, lām ل, mīm م, nūn ن, sīn س, ʿain ع, ṣād ص, qāf ق, rā ر. The six final letters of the Abjadi order (thakhadh ḍaẓagh) are unused. The letters represented correspond to those letters written without Arabic diacritics plus yāʿ ي. It is possible that the restricted set of letters was supposed to invoke an archaic variant of the Arabic alphabet modeled on the Aramaic alphabet.
Certain co-occurrence restrictions are observable in these letters; for instance, ʾAlif is invariably followed by Lām. The substantial majority of the combinations begin either ʾAlif Lām or Ḥāʾ Mīm.
In all but 3 of the 29 cases, these letters are almost immediately followed by mention of the Qur'anic revelation itself (the exceptions are surat al-‘Ankabūt, ar-Rūm and al-Qalam); and some argue that even these three cases should be included, since mention of the revelation is made later on in the surah. More specifically, one may note that in 8 cases the following verse begins "These are the signs...", and in another 5 it begins "The Revelation..."; another 3 begin "By the Qur'an...", and another 2 "By the Book..." Additionally, all but 3 of these suras are Meccan surat (the exceptions are surat al-Baqarah, Āl ʾImrān and ar-Raʻd.)
Lām and Mīm are conjoined and both are written with prolongation mark. One letter is written in two styles. Letter 20:01 is used only in the beginning and middle of a word and that in 19:01 is not used as such. Alif Lām Mīm (الم) is also the first verse of Surah Al-Baqara, Surah Al-Imran, Surah Al-Ankabut, Surah Ar-Rum, Surah Luqman, and Surah As-Sajda.
Abd Allah ibn Abbas and Abdullah ibn Masud, as cited by Abu Hayyan al-Gharnati in his Bahr al-Muhit, are said to have favored the view that these letters stand for words or phrases related to God and His Attributes. The Ahmadi author Muhammad Ali, in his 1917 translation The Holy Qur'an: Text, Translation and Commentary, follows this tradition, giving the following interpretations the letters:
Fakhr al-Din al-Razi, a classical commentator of the Qur'an, has noted some twenty opinions regarding these letters, and mentions multiple opinions that these letters present the names of the Surahs as appointed by God. In addition, he mentions that Arabs would name things after such letters (for example, 'eye' as 'ع', clouds as 'غ', and whale as 'ن').  Amin Ahsan Islahi[year needed] supported al-Razi's opinion, arguing that since these letters are names for Surahs, they are proper nouns. Hamiduddin Farahi similarly attaches symbolic meanings to the letters, e.g. Nun (ن) symbolizing "fish" identifying the sura dedicated to Jonah, or Ta (ط) representing "serpent" introducing suras that mention the story of Prophet Moses and serpents.
Ahsan ur Rehman (2013) claims that there are phonological, syntactic and semantic links between the prefixed letters and the text of the chapters.
Scribal intrusion or corruption
Massey (1996) proposed new evidence for an older theory that the "Mystery Letters" were the initials or monograms of the scribes who originally transcribed the suras.
The Hebrew Theory assumes that the letters represent an import from Biblical Hebrew. Specifically, the combination Alif-Lam would correspond to Hebrew El "god". Abbreviations from Aramaic or Greek have also been suggested.
Christoph Luxenberg in The Syro-Aramaic Reading of the Koran (2000) proposed that substantial portions of the text of the Qur'an were directly taken from Syriac liturgy. His explanation of the disjoined letters is that they are remnants of indications for the liturgical recitation for the Syriac hymns that ended up being copied into the Arabic text.
There have been attempts to give numerological interpretations. Loth (1888) suggested a connection to Gematria. Rashad Khalifa (1974) claimed to have discovered a mathematical code in the Qur'an based on these initials and the number 19. According to his claims, these initials occur throughout their respective chapters in multiples of nineteen. which is mentioned in Sura 74:30
The Báb used the muqatta'at in his Qayyúmu'l-Asmá'. He writes in an early commentary and in his Dalá'il-i-Sab'ih (Seven Proofs) about a hadith from Muhammad al-Baqir (the fifth Shi'i Imam) where it is stated that the first seven surat's muqatta'at have a numerical value of 1267, from which the year 1844 (the year of the Báb's declaration) can be derived.
Sufism has a tradition of attributing mystical significance to the letters. The details differ between schools of Sufism; Sufi tradition generally regards the letters as an extension to the ninety-nine names of God, with some authors offering specific "hidden" meanings for the individual letters.
In 1857–58, Bahá'u'lláh, founder of the Bahá'í Faith, wrote his Commentary on the Isolated Letters (Tafsír-i-Hurúfát-i-Muqatta'ih, also known as Lawh-i-Áyiy-i-Núr, Tablet of the Light Verse). In it, he describes how God created the letters. A black teardrop fell down from the Primordial Pen on the "Perspicuous, Snow-white Tablet", by which the Point was created. The Point then turned into an Alif (vertical stroke), which was again transformed, after which the Muqatta'at appeared. These letters were then differentiated, separated and then again gathered and linked together, appearing as the "names and attributes" of creation. Bahá'u'lláh gives various interpretations of the letters "alif, lam, mim", mostly relating to Allah, trusteeship (wilayah) and the prophethood (nubuwwah) of Muhammad. He emphasizes the central role of the alif in all the worlds of God.
By removing the duplicate letters (leaving only one of each of the 14 initials) and rearranging them, one can create the sentence "نص حكيم قاطع له سر " which could translate to: "a wise and sharp text that has a secret".