if not modules then modules = { } end modules ['math-frc'] = {
    version   = 1.001,
    comment   = "companion to math-frc.mkiv",
    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
    copyright = "PRAGMA ADE / ConTeXt Development Team",
    license   = "see context related readme files"
}

local utfchar   = utf.char

local context   = context
local variables = interfaces.variables

local v_no      = variables.no
local v_yes     = variables.yes
local v_hidden  = variables.hidden

local resolved  = {
    [0x007B] = "\\{",
    [0x007D] = "\\}",
}

table.setmetatableindex(resolved, function(t,k)
    local v = utfchar(k)
    t[k] = v
    return v
end)

local ctx_Uatop = context.Uatop
local ctx_Uover = context.Uover

-- local function umathfraction(how,style,left,right,width)
--     style = tonumber(style) -- or nil
--     if how == v_no then
--         if left == 0x002E and right == 0x002E then
--             if style then
--                 context("\\Uatop style %i",style)
--             else
--                 ctx_Uatop()
--             end
--         else
--             if style then
--                 context("\\Uatopwithdelims style %i %s%s",style,resolved[left],resolved[right])
--             else
--                 context("\\Uatopwithdelims%s%s",resolved[left],resolved[right])
--             end
--         end
--     elseif how == v_yes or how == v_hidden then
--         local norule = how == v_hidden and " norule " or ""
--         if style then
--             if left == 0x002E and right == 0x002E then
--                 context("\\Uabove style %i %s%ssp",style,norule,width)
--             else
--                 context("\\Uabovewithdelims style %i %s%s%s%ssp",style,norule,resolved[left],resolved[right],width)
--             end
--         else
--             if left == 0x002E and right == 0x002E then
--                 context("\\Uabove%s%ssp",norule,width)
--             else
--                 context("\\Uabovewithdelims%s%s%s%ssp",norule,resolved[left],resolved[right],width)
--             end
--         end
--     else -- v_auto
--         if left == 0x002E and right == 0x002E then
--             if style then
--                 context("\\Uover style %i",style)
--             else
--                 ctx_Uover()
--             end
--         else
--             if style then
--                 context("\\Uoverwithdelims style %i %s%s",style,resolved[left],resolved[right])
--             else
--                 context("\\Uoverwithdelims%s%s",resolved[left],resolved[right])
--             end
--         end
--     end
-- end
--
-- interfaces.implement {
--     name      = "umathfraction",
--     actions   = umathfraction,
--     arguments = { "string", "string", "number", "number", "dimen" }
-- }

local function umathfraction(how,left,right,width)
    if how == v_no then
        if left == 0x002E and right == 0x002E then
            ctx_Uatop()
        else
            context("\\Uatopwithdelims%s%s",resolved[left],resolved[right])
        end
    elseif how == v_yes or how == v_hidden then
        local norule = how == v_hidden and " norule " or ""
        if left == 0x002E and right == 0x002E then
            context("\\Uabove %s%ssp",norule,width)
        else
            context("\\Uabovewithdelims %s%s%s%ssp",norule,resolved[left],resolved[right],width)
        end
    else -- v_auto
        if left == 0x002E and right == 0x002E then
            ctx_Uover()
        else
            context("\\Uoverwithdelims%s%s",resolved[left],resolved[right])
        end
    end
end

interfaces.implement {
    name      = "umathfraction",
    actions   = umathfraction,
    protected = true,
    arguments = { "string", "number", "number", "dimen" }
}