Hello all, It seems that ConTeXt's fontloader (hence luaotfload's fontloader) skips to load the VORG table and topSideBearing in the vmtx table These informations are used to get the vertical origin of a glyph.

readers.vorg = function(f,fontdata,specification) reportskippedtable(f,fontdata,"vorg",specification.glyphs) end

readers.vmtx = function(f,fontdata,specification) ... for i=0,nofmetrics-1 do ... if vheight ~= 0 and vheight ~= vdefault then glyph.vheight = vheight end -- if topsidebearing ~= 0 then -- glyph.tsb = topsidebearing -- end

I don't know whether vertical metrics are used in ConTeXt. But, they will be useful for other packages (e.g., LuaTeX-ja) to improve vertical typesetting. Regards Hironori KITAGAWA