The effect of the same restriction depends on the listener’s prior belief. Suppose the listener attributes a letter to Amr, while the speaker says مَا كَتَبَهُ إِلَّا خَالِدٌ—only Khalid wrote it. Replacing a false rival attribution with the correct one yields a reversal (qaṣr al-qalb) reading.
If the listener instead believes both men participated, the utterance excludes joint participation: qaṣr al-ifrād. It does not merely reverse one single false identity.
A structural label derived from the surface form cannot determine these categories without the relevant contextual belief.