Chapter 91 is the dedicated chapter for 'Clocks and watches and parts thereof' in the HS classification system, covering various finished timepieces (such as wristwatches, pocket watches, dashboard clocks, alarm clocks, etc.) as well as their core components (movements, cases, straps, gears, springs, etc.). This chapter is organized according to the hierarchical logic of 'finished products—movements—parts,' with headings 9101 to 9107 covering various finished timepieces, and 9108 to 9114 separately providing headings for movements and dedicated parts. Vehicle clocks and their movements, due to their special usage scenarios, are explicitly included within the scope of this chapter rather than being classified under Chapter 87 as automotive parts. Heading 9108 specifically covers 'complete and assembled clock or watch movements,' i.e., movement assemblies with timekeeping functions that can be directly installed into watch cases or dashboard housings. This heading is further subdivided into multiple subheadings based on power source and use: 9108.1 for electric (including battery- and accumulator-driven) movements, 9108.2 for self-winding movements, 9108.3 for other mechanical movements, and 9108.9 for 'other' movements. Vehicle movements, if electrically or mechanically driven and constituting complete movements, may fall under heading 9108, with the specific subheading depending on their drive method and structural characteristics. Code 910899 consists of six digits. The first 2 digits '91' represent Chapter 91 'Clocks and watches and parts thereof,' confirming that the goods belong to the clock and watch category rather than automotive accessories or electronic components. Digits 3-4 '08' represent heading 9108, i.e., 'complete and assembled clock or watch movements,' distinguished from finished timepieces under 9101-9107 and parts under 9109-9114. Digits 5-6 '99' represent the subheading, which is the residual 'other' item under this heading, meaning that the movement is neither electrically driven (9108.11/9108.19) nor self-winding (9108.20), and is not covered by more specific subheadings such as 9108.91/9108.92. Therefore, 910899 specifically refers to 'other complete assembled movements,' typically applicable in vehicle scenarios to specially structured movements that are neither electric nor self-winding. Vehicle movements are classified under 910899 because they are 'complete and assembled clock or watch movements,' rather than finished timepieces or unassembled parts. If already installed into a dashboard housing to form a finished vehicle clock, they should be classified under 9104 (dashboard clocks and similar clocks); if they are unassembled parts (such as individual gears or springs), they should be classified under 9114. The difference between 910899 and other subheadings of 9108 lies in the drive method: electric under 9108.1, self-winding under 9108.2, other mechanical under 9108.3, while 910899 is the residual item covering complete movements not falling under the above specific subheadings.