Mixed-use districts have been characterized as high-density transit districts whose functions have been compartmentalized on podiums, concourses, decks, towers, and interiors connected with stations. In this paper, I look at the case of Central and Tsim Sha Tsui districts of Hong Kong to answer the following question: If the function mixture of whole buildings becomes visible on the ground, through what receiver pathway would it take place? What can we know about the vertical composition of transit-oriented urbanism from this pathway? The numbers will comprise four observations of district layers: central overall; central above-ground vertical; tims sha tsui overall; and tims sha tsui above-ground vertical. These numbers comprise pure live, pure work, pure visit, mixed function, and without point of interest of 2,566 buildings in Central and 771 buildings in Tsim Sha Tsui. The calculations involve functional visibility, mixed-use retention, Layered Functional Persistence Index (LFPI), layer closure reliability, closed visible composition, Jensen–Shannon divergence, layer transition work, receiver classification, and interface burden equivalence. In Central, there is weak vertical persistence due to the fact that mixed-use retention is 40.44% and visibility retention is 51.61%. Vertical composition in Central approaches the pure live receiver pathway because pure live rises by 36.74 percentage points while pure work, pure visit, and mixed use drop. Tsim Sha Tsui displays greater vertical persistence because its mixed-use retention is 63.80% and visibility retention is 89.44%. Vertical transition of Tsim Sha Tsui is work-receiver oriented since pure work increases by 20.30 percentage points while mixed use falls by 22.10 percentage points. The visit enrichment in lower floors of 14.4 percentage points equals 44.25% of the mixed use incidence loss in Central and 60.01% in Tsim Sha Tsui. These findings prove that volumetric mixed use cannot be assessed by the measure of mixed use incidence. Central and Tsim Sha Tsui differ in persistence, compositional discontinuity, receiver orientation, and lower interface reliance and, therefore, require different planning approaches.