DimensionQuestionEffect
Comparison of qualityDoes the state accompany the action?Identifies a proper ḥāl
Temporal comparisonAre the event-times appropriately related?Tests the timing of the attendant state
In جَاءَ زَيْدٌ يَبْتَسِمُ, smiling during Zayd's arrival is both a sensible manner and a temporally suitable accompaniment. By contrast, an unrelated future prediction should not be reclassified as the circumstance of an earlier event merely because it contains an imperfect.