Hi, If I add properties to math nodes they do not appear in HLIST converted nodes. But if I add attributes they stay to this node for all time. And if I create custom node (for example `user_defined` WHATSIT) then properties doesn't disappear when MLIST is converted to HLIST. EXAMPLE: ``` \documentclass{article} \usepackage[color=no,verbosity=0,channel=log]{nodetree}  \nodetreeregister{preout}  \nodetreeregister{mhlist} \directlua{     %% node.set_properties_mode(true,true)     function set_mathchar_property(n)       if node.type(n.id) == "math_char" then         % set any attribute         node.set_attribute(n, 999, 999)         % set any property         node.setproperty(n, {math_char = true})       elseif node.type(n.id) == "noad" then         if n.nucleus then           set_mathchar_property(n.nucleus)         end       elseif node.type(n.id) == 'sub_mlist' then         set_mathchar_property(n.head)         local USER_MARK   = node.new(node.id("whatsit"), 8)         USER_MARK.type    = 115         USER_MARK.value   = "math added whatsit"         node.set_attribute(USER_MARK, 888, 888)         node.setproperty(USER_MARK, {math_whatsit = true})         n.head = node.insert_before(n.head, n.head, USER_MARK)       end     end     function parse_math_char(h)       set_mathchar_property(h)       return h     end     luatexbase.add_to_callback('pre_mlist_to_hlist_filter', parse_math_char, 'set_mathchar_property') } \begin{document} ${aa}$ \end{document} ``` Here is the output. You can see that after line break only WHATSIT has properties and attributes 888=888, 999=999 stays sticky: ``` Callback: mlist_to_hlist - need_penalties: true - display_type: text ------------------------------------------ └─NOAD   ╚═nucleus:     └─SUB_MLIST       ╚═head:         ├─WHATSIT subtype: user_defined, type: 115, value: math added whatsit, attr: 888=888         │   properties: {['math_whatsit'] = true}         ├─NOAD         │ ╚═nucleus:         │   └─MATH_CHAR fam: 1, char: a, attr: 999=999         │       properties: {['math_char'] = true}         └─NOAD           ╚═nucleus:             └─MATH_CHAR fam: 1, char: a ----------------------- Callback: post_linebreak_filter ------------------------------------------ ├─GLUE subtype: baselineskip, width: 7.69pt └─HLIST subtype: line, width: 345pt, height: 4.31pt   ╚═head:     ├─LOCAL_PAR     ├─HLIST subtype: indent, width: 15pt     ├─MATH     ├─HLIST width: 10.57pt, height: 4.31pt     │ ╚═head:     │   ├─WHATSIT subtype: user_defined, type: 115, value: math added whatsit, attr: 888=888     │   │ ╚═  properties: {['math_whatsit'] = true}     │   ├─GLYPH subtype: 256, char: a, width: 5.29pt, height: 4.31pt, attr: 999=999     │   └─GLYPH subtype: 256, char: a, width: 5.29pt, height: 4.31pt     ├─MATH subtype: endmath     ├─PENALTY subtype: linepenalty, penalty: 10000     ├─GLUE subtype: parfillskip, stretch: +1fil     └─GLUE subtype: rightskip ----------------------- ``` There is setup `node.set_properties_mode(true,true)` which should do something with properties copying but here it does nothing. Could math noad properties be copied to corresponding new noads: - MATH_CHAR  properties moved to  GLYPH; - SUB_MLIST properties moved to  HLIST; - and others depending on conversion Thanks, Linas