2022-12-22 22:16:00

9 files changed, 277 insertions, 325 deletions

diff --git a/source/luametatex/source/luametatex.h b/source/luametatex/source/luametatex.h
index c92599fbc..b46922a11 100644
--- a/source/luametatex/source/luametatex.h
+++ b/source/luametatex/source/luametatex.h
@@ -89,7 +89,7 @@
 # define luametatex_version          210
 # define luametatex_revision         04
 # define luametatex_version_string   "2.10.04"
-# define luametatex_development_id   20221221
+# define luametatex_development_id   20221222
 
 # define luametatex_name_camelcase   "LuaMetaTeX"
 # define luametatex_name_lowercase   "luametatex"
diff --git a/source/luametatex/source/tex/texequivalents.c b/source/luametatex/source/tex/texequivalents.c
index d91663dd3..827f68a77 100644
--- a/source/luametatex/source/tex/texequivalents.c
+++ b/source/luametatex/source/tex/texequivalents.c
@@ -507,6 +507,12 @@ static int tex_aux_save_value(int id)
     return i ? saved_value(i) : 0;
 }
 
+static int tex_aux_save_level(int id)
+{
+    int i = tex_aux_found_save_type(id);
+    return i ? saved_level(i) : 0;
+}
+
 static int tex_aux_saved_box_spec(halfword *packing, halfword *amount)
 {
     int i = tex_aux_found_save_type(box_spec_save_type);
@@ -675,43 +681,47 @@ void tex_show_save_groups(void)
                 tex_confusion("show groups");
                 break;
         }
-        /*tex Show the box context */
-        {
-            int i = tex_aux_save_value(saved_full_spec_item_context);;
-            if (i) {
-                if (i < box_flag) {
-                    /* this is pretty horrible and likely wrong */
-                    singleword cmd = (abs(lmt_nest_state.nest[pointer].mode) == vmode) ? hmove_cmd : vmove_cmd;
-                    tex_print_cmd_chr(cmd, (i > 0) ? move_forward_code : move_backward_code);
-                    tex_print_dimension(abs(i), pt_unit);
-                } else if (i <= max_global_box_flag) {
-                    if (i >= global_box_flag) {
-                        tex_print_str_esc("global");
-                        i -= (global_box_flag - box_flag);
+        /*tex 
+            Show the box context. In traditional \TEX\ the shift is encoded in the context which is 
+            why it had such a large offset for the other context value. That somewhat dirty trick 
+            was has stepwise been removed.
+        */
+        switch (tex_aux_save_value(saved_full_spec_item_context)) {
+            case direct_box_flag:
+                {
+                    scaled shift = tex_aux_save_value(saved_full_spec_item_shift);
+                    if (shift != null_flag) { 
+                        /*tex We passed the safeguard. */
+                        singleword cmd = (abs(lmt_nest_state.nest[pointer].mode) == vmode) ? hmove_cmd : vmove_cmd;
+                        tex_print_cmd_chr(cmd, (shift > 0) ? move_forward_code : move_backward_code);
+                        tex_print_dimension(abs(shift), pt_unit);
                     }
+                }
+                break;
+            case global_box_flag:
+                tex_print_str_esc("global");
+            case box_flag:
+                {
                     tex_print_str_esc("setbox");
-                    tex_print_int(i - box_flag);
+                    tex_print_int(tex_aux_save_level(saved_full_spec_item_context));
                     tex_print_char('=');
-                } else {
-                    switch (i) {
-                        case a_leaders_flag:
-                            tex_print_cmd_chr(leader_cmd, a_leaders);
-                            break;
-                        case c_leaders_flag:
-                            tex_print_cmd_chr(leader_cmd, c_leaders);
-                            break;
-                        case x_leaders_flag:
-                            tex_print_cmd_chr(leader_cmd, x_leaders);
-                            break;
-                        case g_leaders_flag:
-                            tex_print_cmd_chr(leader_cmd, g_leaders);
-                            break;
-                        case u_leaders_flag:
-                            tex_print_cmd_chr(leader_cmd, u_leaders);
-                            break;
-                    }
                 }
-            }
+                break;
+            case a_leaders_flag:
+                tex_print_cmd_chr(leader_cmd, a_leaders);
+                break;
+            case c_leaders_flag:
+                tex_print_cmd_chr(leader_cmd, c_leaders);
+                break;
+            case x_leaders_flag:
+                tex_print_cmd_chr(leader_cmd, x_leaders);
+                break;
+            case g_leaders_flag:
+                tex_print_cmd_chr(leader_cmd, g_leaders);
+                break;
+            case u_leaders_flag:
+                tex_print_cmd_chr(leader_cmd, u_leaders);
+                break;
         }
       FOUND1:
         {
diff --git a/source/luametatex/source/tex/texequivalents.h b/source/luametatex/source/tex/texequivalents.h
index 511463c6a..82e500fb3 100644
--- a/source/luametatex/source/tex/texequivalents.h
+++ b/source/luametatex/source/tex/texequivalents.h
@@ -1788,8 +1788,8 @@ extern halfword tex_explicit_disc_penalty  (halfword mode);
 # define update_tex_tab_skip_local(v)          tex_eq_define(internal_glue_location(tab_skip_code), internal_glue_reference_cmd, v);
 # define update_tex_tab_skip_global(v)        tex_geq_define(internal_glue_location(tab_skip_code), internal_glue_reference_cmd, v);
 
-# define update_tex_box_local(n,v)             tex_eq_define(register_box_location(n) - box_flag,        register_box_reference_cmd, v);
-# define update_tex_box_global(n,v)           tex_geq_define(register_box_location(n) - global_box_flag, register_box_reference_cmd, v);
+# define update_tex_box_local(n,v)             tex_eq_define(register_box_location(n), register_box_reference_cmd, v);
+# define update_tex_box_global(n,v)           tex_geq_define(register_box_location(n), register_box_reference_cmd, v);
 
 # define update_tex_insert_mode(a,v)           tex_word_define(a, internal_int_location(insert_mode_code), v)
 
diff --git a/source/luametatex/source/tex/texmaincontrol.c b/source/luametatex/source/tex/texmaincontrol.c
index aa160968e..62b6d1e1e 100644
--- a/source/luametatex/source/tex/texmaincontrol.c
+++ b/source/luametatex/source/tex/texmaincontrol.c
@@ -662,7 +662,7 @@ static void tex_aux_run_end_group(void) {
 
  */
 
-static void tex_aux_scan_box(int boxcontext, int optional_equal, scaled shift)
+static void tex_aux_scan_box(int boxcontext, int optional_equal, scaled shift, halfword slot)
 {
     /*tex Get the next non-blank non-relax... and optionally skip an equal sign */
     while (1) {
@@ -680,7 +680,7 @@ static void tex_aux_scan_box(int boxcontext, int optional_equal, scaled shift)
     switch (cur_cmd) {
         case make_box_cmd:
             {
-                tex_begin_box(boxcontext, shift);
+                tex_begin_box(boxcontext, shift, slot);
                 return;
             }
         case vcenter_cmd:
@@ -705,7 +705,7 @@ static void tex_aux_scan_box(int boxcontext, int optional_equal, scaled shift)
                                 case vlist_node:
                                 case rule_node:
                                 case glyph_node:
-                                    tex_box_end(boxcontext, boxnode, shift, unset_noad_class);
+                                    tex_box_end(boxcontext, boxnode, shift, unset_noad_class, slot);
                                     return;
                             }
                         }
@@ -720,7 +720,7 @@ static void tex_aux_scan_box(int boxcontext, int optional_equal, scaled shift)
                 halfword v = tex_scan_lua_value(cur_chr);
                 switch (v) {
                     case no_val_level:
-                        tex_box_end(boxcontext, null, shift, unset_noad_class);
+                        tex_box_end(boxcontext, null, shift, unset_noad_class, slot);
                         return;
                     case list_val_level:
                         if (box_leaders_flag(boxcontext)) {
@@ -729,14 +729,14 @@ static void tex_aux_scan_box(int boxcontext, int optional_equal, scaled shift)
                                 case vlist_node:
                                 case rule_node:
                              // case glyph_node:
-                                    tex_box_end(boxcontext, cur_val, shift, unset_noad_class);
+                                    tex_box_end(boxcontext, cur_val, shift, unset_noad_class, slot);
                                     return;
                             }
                         } else {
                             switch (node_type(cur_val)) {
                                 case hlist_node:
                                 case vlist_node:
-                                    tex_box_end(boxcontext, cur_val, shift, unset_noad_class);
+                                    tex_box_end(boxcontext, cur_val, shift, unset_noad_class, slot);
                                     return;
                             }
                         }
@@ -749,7 +749,7 @@ static void tex_aux_scan_box(int boxcontext, int optional_equal, scaled shift)
             {
                 if (box_leaders_flag(boxcontext)) {
                     halfword rulenode = tex_aux_scan_rule_spec(cur_cmd == hrule_cmd ? h_rule_type : (cur_cmd == vrule_cmd ? v_rule_type : m_rule_type), cur_chr);
-                    tex_box_end(boxcontext, rulenode, shift, unset_noad_class);
+                    tex_box_end(boxcontext, rulenode, shift, unset_noad_class, slot);
                     return;
                 } else {
                     break;
@@ -762,7 +762,7 @@ static void tex_aux_scan_box(int boxcontext, int optional_equal, scaled shift)
                     halfword boxnode = null;
                     tex_aux_run_text_char_number();
                     boxnode = tex_pop_tail();
-                    tex_box_end(boxcontext, boxnode, shift, unset_noad_class);
+                    tex_box_end(boxcontext, boxnode, shift, unset_noad_class, slot);
                     return;
                 } else {
                     break;
@@ -776,8 +776,8 @@ static void tex_aux_scan_box(int boxcontext, int optional_equal, scaled shift)
         "that. So you might find something missing in your output. But keep trying; you\n"
         "can fix this later."
     );
-    if (boxcontext == lua_scan_flag) {
-        tex_box_end(boxcontext, null, shift, unset_noad_class);
+    if (boxcontext == lua_scan_flag) { /* hm */
+        tex_box_end(boxcontext, null, shift, unset_noad_class, slot);
     }
 }
 
@@ -791,7 +791,7 @@ static void tex_aux_scan_box(int boxcontext, int optional_equal, scaled shift)
 static void tex_aux_run_move(void) {
     int code = cur_chr;
     halfword val = tex_scan_dimen(0, 0, 0, 0, NULL);
-    tex_aux_scan_box(0, 0, code == move_forward_code ? val : - val);
+    tex_aux_scan_box(direct_box_flag, 0, code == move_forward_code ? val : - val, -1);
 }
 
 /*tex
@@ -903,13 +903,13 @@ static int leader_flags[] = {
 };
 
 static void tex_aux_run_leader(void) {
-    tex_aux_scan_box(leader_flags[cur_chr], 0, null_flag);
+    tex_aux_scan_box(leader_flags[cur_chr], 0, null_flag, -1);
 }
 
 static void tex_aux_run_legacy(void) {
     switch (cur_chr) {
         case shipout_code:
-            tex_aux_scan_box(shipout_flag, 0, null_flag);
+            tex_aux_scan_box(shipout_flag, 0, null_flag, -1);
             break;
         default:
             /* cant_happen */
@@ -922,7 +922,7 @@ static void tex_aux_run_local_box(void) {
 }
 
 static void tex_aux_run_make_box(void) {
-    tex_begin_box(0, null_flag);
+    tex_begin_box(direct_box_flag, null_flag, -1);
 }
 
 /*tex
@@ -1465,7 +1465,7 @@ static void tex_aux_invalid_catcode_table_error(void) {
     tex_handle_error(
         normal_error_type,
         "Invalid \\catcode table",
-        "All \\catcode table ids must be between 0 and " LMT_TOSTRING(max_n_of_catcode_tables-1)
+        "All \\catcode table ids must be between 0 and " LMT_TOSTRING(max_n_of_catcode_tables - 1)
     );
 }
 
@@ -1890,7 +1890,7 @@ halfword tex_local_scan_box(void)
     int old_mode = cur_list.mode;
     int old_level = lmt_main_control_state.local_level;
     cur_list.mode = -hmode;
-    tex_aux_scan_box(lua_scan_flag, 0, null_flag);
+    tex_aux_scan_box(lua_scan_flag, 0, null_flag, -1);
     if (lmt_main_control_state.local_level == old_level) {
         /*tex |\directlua{print(token.scan_list())}\hbox{!}| (n n) */
         if (tracing_nesting_par > 2) {
@@ -2726,125 +2726,122 @@ static void tex_aux_wrapup_leader_box(halfword boxcontext, halfword boxnode)
     }
 }
 
-void tex_box_end(int boxcontext, halfword boxnode, scaled shift, halfword mainclass)
+void tex_box_end(int boxcontext, halfword boxnode, scaled shift, halfword mainclass, halfword slot)
 {
     cur_box = boxnode;
-    if (boxcontext < box_flag) {
-        /*tex
-
-            Append box |boxnode| to the current list, shifted by |boxcontext|. The global variable
-            |adjust_tail| will be non-null if and only if the current box might include adjustments
-            that should be appended to the current vertical list.
-
-            Having shift in the box context is kind of strange but as long as we stay below maxdimen
-            it works.
+    switch (boxcontext) {
+        case direct_box_flag:
+            /*tex
 
-            We now pass the shift directly, so no boxcontext trick here.
+                Append box |boxnode| to the current list, shifted by |boxcontext|. The global variable
+                |adjust_tail| will be non-null if and only if the current box might include adjustments
+                that should be appended to the current vertical list.
 
-        */
+                Having shift in the box context is kind of strange but as long as we stay below maxdimen
+                it works. We now pass the shift directly, so no boxcontext trick here.
 
-        if (boxnode) {
-         // box_shift_amount(boxnode) = boxcontext;
-            if (shift != null_flag) {
-                box_shift_amount(boxnode) = shift;
-            }
-            switch (cur_mode) {
-                case vmode:
-                    if (lmt_packaging_state.pre_adjust_tail) {
-                        if (pre_adjust_head != lmt_packaging_state.pre_adjust_tail) {
-                            tex_inject_adjust_list(pre_adjust_head, 1, boxnode, NULL);
+            */
+            if (boxnode) {
+                if (shift != null_flag) {
+                    box_shift_amount(boxnode) = shift;
+                }
+                switch (cur_mode) {
+                    case vmode:
+                        if (lmt_packaging_state.pre_adjust_tail) {
+                            if (pre_adjust_head != lmt_packaging_state.pre_adjust_tail) {
+                                tex_inject_adjust_list(pre_adjust_head, 1, boxnode, NULL);
+                            }
+                            lmt_packaging_state.pre_adjust_tail = null;
                         }
-                        lmt_packaging_state.pre_adjust_tail = null;
-                    }
-                    if (lmt_packaging_state.pre_migrate_tail) {
-                        if (pre_migrate_head != lmt_packaging_state.pre_migrate_tail) {
-                            tex_append_list(pre_migrate_head, lmt_packaging_state.pre_migrate_tail);
+                        if (lmt_packaging_state.pre_migrate_tail) {
+                            if (pre_migrate_head != lmt_packaging_state.pre_migrate_tail) {
+                                tex_append_list(pre_migrate_head, lmt_packaging_state.pre_migrate_tail);
+                            }
+                            lmt_packaging_state.pre_migrate_tail = null;
                         }
-                        lmt_packaging_state.pre_migrate_tail = null;
-                    }
-                    tex_append_to_vlist(boxnode, lua_key_index(box), NULL);
-                    if (lmt_packaging_state.post_migrate_tail) {
-                        if (post_migrate_head != lmt_packaging_state.post_migrate_tail) {
-                            tex_append_list(post_migrate_head, lmt_packaging_state.post_migrate_tail);
+                        tex_append_to_vlist(boxnode, lua_key_index(box), NULL);
+                        if (lmt_packaging_state.post_migrate_tail) {
+                            if (post_migrate_head != lmt_packaging_state.post_migrate_tail) {
+                                tex_append_list(post_migrate_head, lmt_packaging_state.post_migrate_tail);
+                            }
+                            lmt_packaging_state.post_migrate_tail = null;
                         }
-                        lmt_packaging_state.post_migrate_tail = null;
-                    }
-                    if (lmt_packaging_state.post_adjust_tail) {
-                        if (post_adjust_head != lmt_packaging_state.post_adjust_tail) {
-                            tex_inject_adjust_list(post_adjust_head, 1, null, NULL);
+                        if (lmt_packaging_state.post_adjust_tail) {
+                            if (post_adjust_head != lmt_packaging_state.post_adjust_tail) {
+                                tex_inject_adjust_list(post_adjust_head, 1, null, NULL);
+                            }
+                            lmt_packaging_state.post_adjust_tail = null;
                         }
-                        lmt_packaging_state.post_adjust_tail = null;
-                    }
-                    if (cur_list.mode > nomode) {
-                        if (! lmt_page_builder_state.output_active) {
-                            lmt_page_filter_callback(box_page_context, 0);
+                        if (cur_list.mode > nomode) {
+                            if (! lmt_page_builder_state.output_active) {
+                                lmt_page_filter_callback(box_page_context, 0);
+                            }
+                            tex_build_page();
                         }
-                        tex_build_page();
-                    }
-                    break;
-                case hmode:
-                    cur_list.space_factor = default_space_factor;
-                    tex_couple_nodes(cur_list.tail, boxnode);
-                    cur_list.tail = boxnode;
-                    break;
-             /* case mmode: */
-                default:
-                    boxnode = tex_new_sub_box(boxnode);
-                    tex_couple_nodes(cur_list.tail, boxnode);
-                    cur_list.tail = boxnode;
-                    if (mainclass != unset_noad_class) {
-                        set_noad_classes(boxnode, mainclass);
-                    }
-                    break;
+                        break;
+                    case hmode:
+                        cur_list.space_factor = default_space_factor;
+                        tex_couple_nodes(cur_list.tail, boxnode);
+                        cur_list.tail = boxnode;
+                        break;
+                    /* case mmode: */
+                    default:
+                        boxnode = tex_new_sub_box(boxnode);
+                        tex_couple_nodes(cur_list.tail, boxnode);
+                        cur_list.tail = boxnode;
+                        if (mainclass != unset_noad_class) {
+                            set_noad_classes(boxnode, mainclass);
+                        }
+                        break;
+                }
+            } else {
+                /* just scanning */
             }
-        } else {
-            /* just scanning */
-        }
-    } else if (boxcontext < global_box_flag) {
-        /*tex Store |box| in a local box register  */
-        update_tex_box_local(boxcontext, boxnode);
-    } else if (boxcontext <= max_global_box_flag) {
-        /*tex Store |box| in a global box register  */
-        update_tex_box_global(boxcontext, boxnode);
-    } else {
-        switch (boxcontext) {
-            case shipout_flag:
-                /*tex This normally can't happen as some backend code needs to kick in. */
-                if (boxnode) {
-                    /*tex We just show the box ... */
-                    tex_begin_diagnostic();
-                    tex_show_node_list(boxnode, max_integer, max_integer);
-                    tex_end_diagnostic();
-                    /*tex ... and wipe it when it's a register ... */
-                    if (box_register(boxnode)) {
-                        tex_flush_node_list(boxnode);
-                        box_register(boxnode) = null;
-                    }
-                    /*tex ... so there is at least an indication that we flushed. */
+            break;
+        case box_flag:
+            /*tex Store |box| in a local box register  */
+            update_tex_box_local(slot, boxnode);
+            break;
+        case global_box_flag:
+            /*tex Store |box| in a global box register  */
+            update_tex_box_global(slot, boxnode);
+            break;
+        case shipout_flag:
+            /*tex This normally can't happen as some backend code needs to kick in. */
+            if (boxnode) {
+                /*tex We just show the box ... */
+                tex_begin_diagnostic();
+                tex_show_node_list(boxnode, max_integer, max_integer);
+                tex_end_diagnostic();
+                /*tex ... and wipe it when it's a register ... */
+                if (box_register(boxnode)) {
+                    tex_flush_node_list(boxnode);
+                    box_register(boxnode) = null;
                 }
-                break;
-            case left_box_flag:
-            case right_box_flag:
-            case middle_box_flag:
-                /*tex Actualy, this cannot happen ... will go away. */
-                tex_aux_finish_local_box();
-                break;
-            case lua_scan_flag:
-                /*tex We are done with scanning so let's return to the caller. */
-                tex_aux_wrapup_local_scan_box();
-                cur_box = boxnode;
-                break;
-            case a_leaders_flag:
-            case c_leaders_flag:
-            case x_leaders_flag:
-            case g_leaders_flag:
-            case u_leaders_flag:
-                tex_aux_wrapup_leader_box(boxcontext, boxnode);
-                break;
-            default:
-                /* fatal error */
-                break;
-        }
+                /*tex ... so there is at least an indication that we flushed. */
+            }
+            break;
+        case left_box_flag:
+        case right_box_flag:
+        case middle_box_flag:
+            /*tex Actualy, this cannot happen ... will go away. */
+            tex_aux_finish_local_box();
+            break;
+        case lua_scan_flag:
+            /*tex We are done with scanning so let's return to the caller. */
+            tex_aux_wrapup_local_scan_box();
+            cur_box = boxnode;
+            break;
+        case a_leaders_flag:
+        case c_leaders_flag:
+        case x_leaders_flag:
+        case g_leaders_flag:
+        case u_leaders_flag:
+            tex_aux_wrapup_leader_box(boxcontext, boxnode);
+            break;
+        default:
+            /* fatal error */
+            break;
     }
 }
 
@@ -2858,76 +2855,6 @@ void tex_box_end(int boxcontext, halfword boxnode, scaled shift, halfword maincl
 
 */
 
-// void tex_begin_paragraph(int doindent, int context)
-// {
-//     halfword q;
-//     int indented = doindent;
-//     int isvmode = cur_list.mode == vmode;
-//     if (isvmode || cur_list.head != cur_list.tail) {
-//          /*tex
-//              Actually we could remove the callback and hook it into the |\everybeforepar| but that one
-//              started out as a |tex.expandmacro| itself and we don't want the callback overhead every
-//              time, so now we have both. However, in the end I decided to do this one {\em before} the
-//              parskip is injected.
-//          */
-//          if (every_before_par_par) {
-//              tex_begin_inserted_list(tex_get_available_token(token_val(end_local_cmd, 0)));
-//              tex_begin_token_list(every_before_par_par, every_before_par_text);
-//              if (tracing_nesting_par > 2) {
-//                  tex_local_control_message("entering local control via \\everybeforepar");
-//              }
-//              tex_local_control(1);
-//          }
-//       // if (type(cur_list.tail) == glue_node && subtype(cur_list.tail) == par_skip_glue) {
-//       //     /* ignore */
-//       // } else {
-//              tex_tail_append(tex_new_param_glue_node(par_skip_code, par_skip_glue));
-//       // }
-//     }
-//     lmt_begin_paragraph_callback(isvmode, &indented, context);
-//     /*tex We'd better not messed up things in the callback! */
-//     cur_list.prev_graf = 0;
-//     tex_push_nest();
-//     cur_list.mode = hmode;
-//     cur_list.space_factor = default_space_factor;
-//     /*tex  Add local paragraph node */
-//     tex_tail_append(tex_new_par_node(vmode_par_par_subtype));
-//  // if (end_of_par_par) {
-//  //     update_tex_end_of_par(null); /* option */
-//  // }
-//     q = cur_list.tail;
-//     /*tex We will move this to after the dir nodes have been dealt with. */
-//     tex_aux_insert_parindent(indented);
-//     /*tex Dir nodes end up before the indent box. */
-//     {
-//         halfword dir_rover = lmt_dir_state.text_dir_ptr;
-//         while (dir_rover) {
-//             if ((node_next(dir_rover)) || (dir_direction(dir_rover) != par_direction_par)) {
-//                 halfword dir_graf_tmp = tex_new_dir(normal_dir_subtype, dir_direction(dir_rover));
-//                 tex_try_couple_nodes(dir_graf_tmp, node_next(q));
-//                 tex_couple_nodes(q, dir_graf_tmp);
-//             }
-//             dir_rover = node_next(dir_rover);
-//         }
-//     }
-//     /*tex We might need to go to the last injected dir and/or indent node. */
-//     while (node_next(q)) {
-//         q = node_next(q);
-//     }
-//     cur_list.tail = q;
-//     /*tex The |\everypar| tokens are injected after dir nodes have been added. */
-//     if (every_par_par) {
-//         tex_begin_token_list(every_par_par, every_par_text);
-//     }
-//     if (lmt_nest_state.nest_data.ptr == 1) {
-//         if (! lmt_page_builder_state.output_active) {
-//             lmt_page_filter_callback(begin_paragraph_page_context, 0);
-//         }
-//         /*tex put |par_skip| glue on current page */
-//         tex_build_page();
-//     }
-// }
-
 void tex_tail_prepend(halfword n) 
 {
     tex_couple_nodes(node_prev(cur_list.tail), n);
@@ -3048,7 +2975,7 @@ static void tex_aux_run_kern(void)
 {
     halfword code = cur_chr;
     switch (code) {
-        /* not yet enabled and maybe it never wil be */
+        /* not yet enabled and maybe it never will be */
         case h_kern_code:
             if (cur_mode == vmode) {
                 tex_back_input(token_val(kern_cmd, normal_kern_code));
@@ -4227,9 +4154,9 @@ static void tex_aux_set_box_property(void)
 
 static void tex_aux_set_box(int a)
 {
-    halfword n = tex_scan_box_register_number() + (is_global(a) ? global_box_flag : box_flag);
+    halfword slot = tex_scan_box_register_number();
     if (lmt_error_state.set_box_allowed) {
-        tex_aux_scan_box(n, 1, null_flag);
+        tex_aux_scan_box(is_global(a) ? global_box_flag : box_flag, 1, null_flag, slot);
     } else {
         tex_handle_error(
             normal_error_type,
@@ -5492,32 +5419,22 @@ static int tex_aux_set_some_item(halfword a)
 
 static void tex_aux_set_constant_register(halfword cmd, halfword cs, halfword flags)
 {
+    halfword v = null;
     switch(cmd) {
         case integer_cmd:
-            {
-                halfword v = tex_scan_int(1, NULL);
-                tex_define(flags, cs, integer_cmd, v);
-            }
+            v = tex_scan_int(1, NULL);
             break;
         case dimension_cmd:
-            {
-                scaled v = tex_scan_dimen(0, 0, 0, 1, NULL);
-                tex_define(flags, cs, dimension_cmd, v);
-            }
+            v = tex_scan_dimen(0, 0, 0, 1, NULL);
             break;
         case gluespec_cmd:
-            {
-                halfword v = tex_scan_glue(glue_val_level, 1);
-                tex_define(flags, cs, gluespec_cmd, v);
-            }
+            v = tex_scan_glue(glue_val_level, 1);
             break;
         case mugluespec_cmd:
-            {
-                halfword v = tex_scan_glue(mu_val_level, 1);
-                tex_define(flags, cs, mugluespec_cmd, v);
-            }
+            v = tex_scan_glue(mu_val_level, 1);
             break;
     }
+    tex_define(flags, cs, cmd, v);
 }
 
 void tex_run_prefixed_command(void)
diff --git a/source/luametatex/source/tex/texmaincontrol.h b/source/luametatex/source/tex/texmaincontrol.h
index b71aaedac..5b72a3d43 100644
--- a/source/luametatex/source/tex/texmaincontrol.h
+++ b/source/luametatex/source/tex/texmaincontrol.h
@@ -52,7 +52,7 @@ extern void     tex_you_cant_error                  (const char *helpinfo);
 extern void     tex_off_save                        (void);
 
 extern halfword tex_local_scan_box                  (void);
-extern void     tex_box_end                         (int boxcontext, halfword boxnode, scaled shift, halfword mainclass);
+extern void     tex_box_end                         (int boxcontext, halfword boxnode, scaled shift, halfword mainclass, halfword slot);
 
 extern void     tex_get_r_token                     (void);
 
diff --git a/source/luametatex/source/tex/texmath.c b/source/luametatex/source/tex/texmath.c
index ffc73cd12..ec30de1ca 100644
--- a/source/luametatex/source/tex/texmath.c
+++ b/source/luametatex/source/tex/texmath.c
@@ -2458,53 +2458,70 @@ halfword tex_math_make_disc(halfword d)
 void tex_run_math_modifier(void)
 {
     halfword tail = cur_list.tail;
-    if (cur_list.head != tail && node_type(tail) == simple_noad) { // maybe all
-        switch (cur_chr) {
-            case adapt_to_left_modifier_code:
-                noad_options(tail) = unset_option(noad_options(tail), noad_option_adapt_to_right_size);
-                noad_options(tail) |= noad_option_adapt_to_left_size;
-                break;
-            case adapt_to_right_modifier_code:
-                noad_options(tail) = unset_option(noad_options(tail), noad_option_adapt_to_left_size);
-                noad_options(tail) |= noad_option_adapt_to_right_size;
-                break;
-            /* todo: actually this one can also be used for other types */
-            case axis_modifier_code:
-                noad_options(tail) |= noad_option_axis;
-                break;
-            case no_axis_modifier_code:
-                noad_options(tail) |= noad_option_no_axis;
-                break;
-            case phantom_modifier_code:
-                noad_options(tail) |= noad_option_phantom;
-                break;
-            case void_modifier_code:
-                noad_options(tail) |= noad_option_void;
-                break;
-            case source_modifier_code:
-                if (tex_scan_keyword("nucleus")) {
-                    noad_options(tail) |= noad_option_source_on_nucleus;    
+    if (cur_list.head != tail) {
+        switch (node_type(tail)) {
+            case simple_noad:
+                switch (cur_chr) {
+                    case adapt_to_left_modifier_code:
+                        noad_options(tail) = unset_option(noad_options(tail), noad_option_adapt_to_right_size);
+                        noad_options(tail) |= noad_option_adapt_to_left_size;
+                        break;
+                    case adapt_to_right_modifier_code:
+                        noad_options(tail) = unset_option(noad_options(tail), noad_option_adapt_to_left_size);
+                        noad_options(tail) |= noad_option_adapt_to_right_size;
+                        break;
+                    /* todo: actually this one can also be used for other types */
+                    case axis_modifier_code:
+                        noad_options(tail) |= noad_option_axis;
+                        break;
+                    case no_axis_modifier_code:
+                        noad_options(tail) |= noad_option_no_axis;
+                        break;
+                    case phantom_modifier_code:
+                        noad_options(tail) |= noad_option_phantom;
+                        break;
+                    case void_modifier_code:
+                        noad_options(tail) |= noad_option_void;
+                        break;
+                    case source_modifier_code:
+                        if (tex_scan_keyword("nucleus")) {
+                            noad_options(tail) |= noad_option_source_on_nucleus;    
+                        }
+                        noad_source(tail) = tex_scan_int(0, NULL);
+                        break;
+                    case openup_height_modifier_code:
+                        noad_options(tail) |= noad_option_openup_height;
+                        noad_height(tail) = tex_scan_dimen(0, 0, 0, 0, NULL);
+                        break;
+                    case openup_depth_modifier_code:
+                        noad_options(tail) |= noad_option_openup_depth;
+                        noad_depth(tail) = tex_scan_dimen(0, 0, 0, 0, NULL);
+                        break;
+                    case display_limits_modifier_code:
+                        noad_options(tail) = unset_option(noad_options(tail), noad_option_limits | noad_option_no_limits);
+                        break;
+                    case limits_modifier_code:
+                        noad_options(tail) = unset_option(noad_options(tail), noad_option_no_limits);
+                        noad_options(tail) |= noad_option_limits;
+                        break;
+                    case no_limits_modifier_code:
+                        noad_options(tail) = unset_option(noad_options(tail), noad_option_limits);
+                        noad_options(tail) |= noad_option_no_limits;
+                        break;
+                }
+            default:
+                switch (node_type(tail)) {
+                    case accent_noad:
+                        switch (cur_chr) {
+                            case source_modifier_code:
+                                if (tex_scan_keyword("nucleus")) {
+                                    noad_options(tail) |= noad_option_source_on_nucleus;    
+                                }
+                                noad_source(tail) = tex_scan_int(0, NULL);
+                                break;
+                        }
+
                 }
-                noad_source(tail) = tex_scan_int(0, NULL);
-                break;
-            case openup_height_modifier_code:
-                noad_options(tail) |= noad_option_openup_height;
-                noad_height(tail) = tex_scan_dimen(0, 0, 0, 0, NULL);
-                break;
-            case openup_depth_modifier_code:
-                noad_options(tail) |= noad_option_openup_depth;
-                noad_depth(tail) = tex_scan_dimen(0, 0, 0, 0, NULL);
-                break;
-            case display_limits_modifier_code:
-                noad_options(tail) = unset_option(noad_options(tail), noad_option_limits | noad_option_no_limits);
-                break;
-            case limits_modifier_code:
-                noad_options(tail) = unset_option(noad_options(tail), noad_option_no_limits);
-                noad_options(tail) |= noad_option_limits;
-                break;
-            case no_limits_modifier_code:
-                noad_options(tail) = unset_option(noad_options(tail), noad_option_limits);
-                noad_options(tail) |= noad_option_no_limits;
                 break;
         }
     }
diff --git a/source/luametatex/source/tex/texpackaging.c b/source/luametatex/source/tex/texpackaging.c
index 9b7ff31bf..49a18497c 100644
--- a/source/luametatex/source/tex/texpackaging.c
+++ b/source/luametatex/source/tex/texpackaging.c
@@ -65,7 +65,7 @@
 
  */
 
-static void tex_aux_scan_full_spec(quarterword c, quarterword spec_direction, int just_pack, scaled shift)
+static void tex_aux_scan_full_spec(halfword context, quarterword c, quarterword spec_direction, int just_pack, scaled shift, halfword slot)
 {
     quarterword spec_code = packing_additional;
     int spec_amount = 0;
@@ -85,7 +85,6 @@ static void tex_aux_scan_full_spec(quarterword c, quarterword spec_direction, in
     halfword state = 0;
     halfword retain = 0;
     halfword mainclass = unset_noad_class;
-    int context = saved_value(saved_full_spec_item_context);
     int brace = 0;
     while (1) {
         /*tex Maybe |migrate <int>| makes sense here. */
@@ -300,7 +299,7 @@ static void tex_aux_scan_full_spec(quarterword c, quarterword spec_direction, in
     /*tex Now we're referenced. We need to preserve this over the group. */
     add_attribute_reference(attrlist);
     /* */
-    tex_set_saved_record(saved_full_spec_item_context, box_context_save_type, 0, context);
+    tex_set_saved_record(saved_full_spec_item_context, box_context_save_type, slot, context); /* slot fits in a quarterword */
     /*tex Traditionally these two are packed into one record: */
     tex_set_saved_record(saved_full_spec_item_packaging, box_spec_save_type, spec_code, spec_amount);
     /*tex Adjust |text_dir_ptr| for |scan_spec|: */
@@ -2320,7 +2319,7 @@ halfword tex_filtered_vpack(halfword p, scaled h, int m, scaled maxdepth, int gr
 
 void tex_run_vcenter(void)
 {
-    tex_aux_scan_full_spec(vcenter_group, direction_l2r, 0, 0);
+    tex_aux_scan_full_spec(direct_box_flag, vcenter_group, direction_l2r, 0, 0, -1);
     tex_normal_paragraph(vcenter_par_context);
     tex_push_nest();
     cur_list.mode = -vmode;
@@ -2398,13 +2397,14 @@ static scaled tex_aux_first_height(halfword boxnode)
 
 void tex_package(singleword nature)
 {
-    halfword context, spec, dirptr, attrlist, justpack, orientation, anchor, geometry, source, target, axis, mainclass, state, retain;
+    halfword slot, context, spec, dirptr, attrlist, justpack, orientation, anchor, geometry, source, target, axis, mainclass, state, retain;
     scaled shift;
     int grp = cur_group;
     scaled maxdepth = box_max_depth_par;
     halfword boxnode = null; /*tex Aka |cur_box|. */
     tex_unsave();
     lmt_save_state.save_stack_data.ptr -= saved_full_spec_n_of_items;
+    slot = saved_level(saved_full_spec_item_context);
     context = saved_value(saved_full_spec_item_context);
     spec = saved_value(saved_full_spec_item_packaging);
     dirptr = saved_value(saved_full_spec_item_direction);
@@ -2536,7 +2536,7 @@ void tex_package(singleword nature)
     box_axis(boxnode) = (singleword) axis;
     box_package_state(boxnode) |= (singleword) state;
     tex_pop_nest();
-    tex_box_end(context, boxnode, shift, mainclass);
+    tex_box_end(context, boxnode, shift, mainclass, slot);
 }
 
 void tex_run_unpackage(void)
@@ -2786,7 +2786,7 @@ void tex_run_unpackage(void)
 
 */
 
-inline static halfword tex_aux_depth_correction(halfword b, const line_break_properties *properties)
+static halfword tex_aux_depth_correction(halfword b, const line_break_properties *properties)
 {
     /*tex The deficiency of space between baselines: */
     halfword p;
@@ -3227,7 +3227,7 @@ halfword tex_vsplit(halfword n, scaled h, int m)
 
 */
 
-void tex_begin_box(int boxcontext, scaled shift)
+void tex_begin_box(int boxcontext, scaled shift, halfword slot)
 {
     halfword code = cur_chr;
     halfword boxnode = null; /*tex Aka |cur_box|. */
@@ -3392,7 +3392,6 @@ void tex_begin_box(int boxcontext, scaled shift)
                         break;
                 }
                 mode = code - vtop_code;
-                tex_set_saved_record(saved_full_spec_item_context, box_context_save_type, 0, boxcontext);
                 switch (abs(cur_list.mode)) {
                     case vmode:
                         spec_direction = dir_lefttoright;
@@ -3405,16 +3404,16 @@ void tex_begin_box(int boxcontext, scaled shift)
                         break;
                 }
                 if (mode == hmode) {
-                    if ((boxcontext < box_flag) && (abs(cur_list.mode) == vmode)) {
-                        tex_aux_scan_full_spec(adjusted_hbox_group, spec_direction, just_pack, shift);
+                    if ((boxcontext == direct_box_flag) && (abs(cur_list.mode) == vmode)) {
+                        tex_aux_scan_full_spec(boxcontext, adjusted_hbox_group, spec_direction, just_pack, shift, slot);
                     } else {
-                        tex_aux_scan_full_spec(hbox_group, spec_direction, just_pack, shift);
+                        tex_aux_scan_full_spec(boxcontext, hbox_group, spec_direction, just_pack, shift, slot);
                     }
                 } else {
                     if (mode == vmode) {
-                        tex_aux_scan_full_spec(vbox_group, spec_direction, just_pack, shift);
+                        tex_aux_scan_full_spec(boxcontext, vbox_group, spec_direction, just_pack, shift, slot);
                     } else {
-                        tex_aux_scan_full_spec((code == dbox_code || code == dpack_code) ? dbox_group : vtop_group, spec_direction, just_pack, shift);
+                        tex_aux_scan_full_spec(boxcontext, (code == dbox_code || code == dpack_code) ? dbox_group : vtop_group, spec_direction, just_pack, shift, slot);
                         mode = vmode;
                     }
                     tex_normal_paragraph(vmode_par_context);
@@ -3437,5 +3436,5 @@ void tex_begin_box(int boxcontext, scaled shift)
             }
     }
     /*tex In simple cases, we use the box immediately. */
-    tex_box_end(boxcontext, boxnode, shift, unset_noad_class);
+    tex_box_end(boxcontext, boxnode, shift, unset_noad_class, slot);
 }
diff --git a/source/luametatex/source/tex/texpackaging.h b/source/luametatex/source/tex/texpackaging.h
index 5fd4bf9e4..0e3c0a471 100644
--- a/source/luametatex/source/tex/texpackaging.h
+++ b/source/luametatex/source/tex/texpackaging.h
@@ -179,29 +179,37 @@ extern void      tex_run_vcenter          (void);
     |box_code|, |copy_code|, |last_box_code|, |vsplit_code|, |vtop_code|, |vtop_code + vmode|, and
     |vtop_code + hmode|, where the latter two are used denote |\vbox| and |\hbox|, respectively.
 
+    Originally the shift was encoded in the box context in case of a move. In fact even the local 
+    and global register assignments were in that property but this is no longer the case. This
+    actually makes implementing a |\boxspecdef| cleaner (a discarded experiment). The intermediate 
+    cleasned up flags can be found in the history. 
+
 */
 
 # define biggest_reg 65535  /*tex This could be in |textypes.h|. */
 
 typedef enum box_flags {
-    box_flag            = 010000000000,                        /*tex context code for |\setbox0| (< maxdimen) */
-    global_box_flag     = 010000000000 +     biggest_reg,      /*tex context code for |\global\setbox0| */
-    max_global_box_flag = 010000000000 + 2 * biggest_reg,
-    left_box_flag       = 010000000000 + 2 * biggest_reg +  1, /*tex context code for |\localleftbox| (not used) */
-    right_box_flag      = 010000000000 + 2 * biggest_reg +  2, /*tex context code for |\localrightbox| (not used) */
-    middle_box_flag     = 010000000000 + 2 * biggest_reg +  3, /*tex context code for |\localrightbox| (not used) */
-    shipout_flag        = 010000000000 + 2 * biggest_reg +  4, /*tex context code for |\shipout| */
-    lua_scan_flag       = 010000000000 + 2 * biggest_reg +  5, /*tex context code for |scan_list| */
-    a_leaders_flag      = 010000000000 + 2 * biggest_reg +  6, /*tex context code for |\leaders| */
-    c_leaders_flag      = 010000000000 + 2 * biggest_reg +  7, /*tex context code for |\cleaders| */
-    x_leaders_flag      = 010000000000 + 2 * biggest_reg +  8, /*tex context code for |\xleaders| */
-    g_leaders_flag      = 010000000000 + 2 * biggest_reg +  9, /*tex context code for |\gleaders| */
-    u_leaders_flag      = 010000000000 + 2 * biggest_reg + 10, /*tex context code for |\uleaders| */
+    direct_box_flag     = 0x00,
+ /* moved_box_flag      = 0x01, */
+ /* vcenter_box_flag    = 0x02, */ 
+    box_flag            = 0x02, /*tex context code for |\setbox0| */
+    global_box_flag     = 0x03, /*tex context code for |\global\setbox0| */
+    left_box_flag       = 0x04, /*tex context code for |\localleftbox| */
+    right_box_flag      = 0x05, /*tex context code for |\localrightbox| */
+    middle_box_flag     = 0x06, /*tex context code for |\localrightbox| */
+    shipout_flag        = 0x07, /*tex context code for |\shipout| */
+    lua_scan_flag       = 0x08, /*tex context code for |scan_list| */
+    a_leaders_flag      = 0x09, /*tex context code for |\leaders| */
+    c_leaders_flag      = 0x0A, /*tex context code for |\cleaders| */
+    x_leaders_flag      = 0x0B, /*tex context code for |\xleaders| */
+    g_leaders_flag      = 0x0C, /*tex context code for |\gleaders| */
+    u_leaders_flag      = 0x0D, /*tex context code for |\uleaders| */
+
 } box_flags;
 
 # define box_leaders_flag(f) (f >= a_leaders_flag && f <= u_leaders_flag)
 
-extern void tex_begin_box        (int boxcontext, scaled shift);
+extern void tex_begin_box        (int boxcontext, scaled shift, halfword slot);
 extern int  tex_ignore_math_skip (halfword p);
 
 # endif
diff --git a/source/luametatex/source/tex/textypes.h b/source/luametatex/source/tex/textypes.h
index 0fa80dd99..12a0aadf9 100644
--- a/source/luametatex/source/tex/textypes.h
+++ b/source/luametatex/source/tex/textypes.h
@@ -170,7 +170,8 @@ extern halfword tex_badness(
 # define semi_tight_criterium                      12 /* same as |decent_criterium| */
 
 # define default_rule                           26214 /*tex 0.4pt */
-# define ignore_depth                       -65536000 /*tex The magic dimension value to mean \quote {ignore me}. */
+# define ignore_depth                       -65536000 /*tex The magic dimension value to mean \quote {ignore me}: -1000pt */
+# define ignore_depth_zero_baselineskip    -131072000 /*tex Idem but keep zero skip: -2000pt */
 
 # define min_quarterword                            0 /*tex The smallest allowable value in a |quarterword|. */
 # define max_quarterword                        65535 /*tex The largest allowable value in a |quarterword|. */