Original text: أَمَّا الْمَعْرِفَةُ، فَلَا يُعْتَبَرُ فِي مَنْعِ الصَّرْفِ بِهَا إِلَّا الْعَلَمِيَّةُ.
Translation: Among forms of definiteness, proper-name status is the relevant cause of diptote status.
Original text: وَتَجْتَمِعُ مَعَ غَيْرِ الْوَصْفِ.
Translation: Proper-name status may combine with causes other than adjectival status.
Remember: not every proper name is a diptote, not every definite noun is a proper name, and not every word lacking tanwīn is a diptote. The next passage explains foreign origin in detail.