What direction of restriction is described for «Zayd huwa al-qāʾim»?

The Separating Pronoun (Ḍamīr al-Faṣl): Restriction, Emphasis and Predication

• Making standing Zayd’s only possible property
• Ascribing standing to both Zayd and ʿAmr
• Asking who is standing
• Restricting standing to Zayd