A hierarchical map numbering system divides a country's territory into progressively finer grid cells to uniquely identify topographic map sheets at standard cartographic scales. Starting from a coarse 4°×4° block (identified by a base number), each level subdivides the parent block into 16 equal parts (labeled A–P, then 1–16, then NW/NE/SW/SE), with each subdivision level corresponding to a finer map scale (1:250,000 → 1:50,000 → 1:25,000); a location's full sheet number is derived from its latitude and longitude by successively locating which sub-block it falls within at each level. This system belongs to the domain of surveying and cartography, specifically map indexing and geodetic reference systems, and is a specific national implementation (used by a national survey/mapping organization) of a general international principle for organizing multi-scale map sheet series and generating adjacent-sheet indices.
A hierarchical map numbering system divides a country's territory into progressively finer grid cells to uniquely identify topographic map sheets at standard cartographic scales. Starting from a coar…