What does “mawqūfah ilā istibānat ḥālihi” mean in this context?

Narrator Anonymity: Wuḥdān, Mubham, Majhūl al-ʿAyn and Mastūr

• It is necessarily mawqūf to a Companion
• It has permanently been accepted as sound
• Withhold a final acceptance-or-rejection verdict until the person’s state is clarified
• No Companion appears in the chain