What are the Luminous Letters, and are they the Seven Oft-Repeated Verses?

The term "Nuranic letters" (الحروف النورانية) is used by some to refer to the disconnected letters (الحروف المقطعة) found at the beginning of some surahs, which number fourteen letters. There is no origin for this designation from the Prophet (peace be upon him) or the Salaf. Furthermore, some divide the Arabic alphabet into Nuranic (those found in Al-Fatiha and at the beginning of surahs) and Zulmanic (ظلمانية) (those not found in them). Applying this description to the letters of the Qur'an is not permissible due to the absence of divine revelation to substantiate it, which might be considered delving into the Book of Allah without knowledge. As for "the seven oft-repeated verses" (السبع المثاني), it refers to Surah Al-Fatiha.