وَالْأَلِفُ وَاللَّامُ بِمَعْنَى «الَّذِي»، وَصِلَتُهُ اسْمُ الْفَاعِلِ وَاسْمُ الْمَفْعُولِ.
Translation: The text treats al- as relative in some constructions, where an active or passive participle functions as its ṣilah.
This is the special classical analysis of relative al-. Not every al- is relative; e.g., the al- of «الْكِتَابُ» can simply mark definiteness.
The next two source examples show active and passive participles.