Here the resulting event uses Form VII, but the initiating action belongs to Form IV (ifʿāl).
أَغْلَقْتُ الْبَابَ فَانْغَلَقَ
Translation: I closed the door, and it became closed.
أَغْلَقْتُ is Form IV, with the speaker acting on the door. اِنْغَلَقَ is Form VII and reports the door's resulting state. The source specifically places this under Form VII's response to Form IV.
LessonsCharacteristics of Form VII (Infiʿāl): Intransitivity, Manifestation, Resulting Action, Equivalence, Root Restrictions and Independent UseQuiz
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Fourth Characteristic: Response to Form IV
Here the resulting event uses Form VII, but the initiating action belongs to Form IV (ifʿāl).
أَغْلَقْتُ الْبَابَ فَانْغَلَقَ
Translation: I closed the door, and it became closed.
أَغْلَقْتُ is Form IV, with the speaker acting on the door. اِنْغَلَقَ is Form VII and reports the door's resulting state. The source specifically places this under Form VII's response to Form IV.