مَا سَافَرَ إِلَّا زَيْدٌ.
No one travelled except Zayd.
If the listener believes that both Zayd and ʿAmr travelled, the restriction can remove the wrongly included second traveller (ifrād). If the listener believed ʿAmr alone travelled, the statement may reverse the belief (qalb).
Taʿyīn occurs when the listener is undecided among alternatives. The type of restriction is determined by the belief being corrected, not merely by its grammatical form.