How does al-ṣalāt al-wusṭā relate to al-ṣalawāt?

Iṭnāb: Clarification after Ambiguity, Tawshīʿ, Repetition and Īghāl

• It is included in the prayers but singled out for emphasis
• A separate class excluded from the general by conjunction
• A contradictory ruling to the first general expression
• One of the two unnamed components of a tawshīʿ expression