[votan]

The "general" sub-category is the value nil.

function addon:InitialAchievements()
    local function GetAchievements(topLevelIndex, categoryIndex, numAchievements)
        for achievementIndex = 1, numAchievements do
            local achievementId = GetAchievementId(topLevelIndex, categoryIndex, achievementIndex)
-- ...
        end
    end
 
    local numCategories = GetNumAchievementCategories()
    for topLevelIndex = 1, numCategories do
        local _, numSubCatgories, numAchievements = GetAchievementCategoryInfo(topLevelIndex)
        -- General
        GetAchievements(topLevelIndex, nil, numAchievements)
        for subCategoryIndex = 1, numSubCatgories do
            local _, numAchievements = GetAchievementSubCategoryInfo(topLevelIndex, subCategoryIndex)
            GetAchievements(topLevelIndex, subCategoryIndex, numAchievements)
        end
    end
end