How did Westcott and Hort classify New Testament manuscript witnesses?

In the field of textual criticism, the English scholars B.F. Westcott and F.J.A. Hort classified New Testament manuscript witnesses into four distinct groupings in their 1881–82 edition:1

• Neutral: Represented by manuscripts such as B and ℵ, this was considered the purest and earliest Eastern text.1
• Alexandrian: Characterized as a smoothed version of the Neutral text as it developed in Alexandria.1
• Western: Represented by D, the Old Syrian, and Old Latin (O.L.) versions, along with the Western Fathers; this group was noted for including glosses that led to the rejection of many readings.1
• Syrian: Comprising A and the later Byzantine tradition.1

Westcott and Hort used this classification to demonstrate that the Textus Receptus—and by extension the King James Version—was based on an inferior, later text type, whereas their edition prioritized the superior Neutral and Alexandrian types.1