In addition to clumps, another set of structures, called ``filters,'' are used to better support vectorized processing of columns and PFTs. Filters group like columns or PFTs based on their process-specific categorization. Like clumps, filters contain a vector of array indices and are used for indirect addressing into the main data structure hierarchy. Filters are created in initFilters (Section A.55.1) for snow, non-snow, lake, non-lake, vegetated, and bare soil columns and PFTs for each clump of gridcells. Most filters are initialized once, but the snow and non-snow filters must be reconstructed as snowfall and melting occur, and the vegetated PFT filter must be reconstructed in DGVM as die-off and establishment occur.