To write the Tables element (Tb) in the index.

§1. Indexing. Tables inside extensions are often used just for the storage needed to manage back-of-house algorithms, so to speak, and they aren't intended for the end user to poke around with; that's certainly true of the tables in the Standard Rules, which of course are always present. So these are hidden by default. 

void TablesElement::render(OUTPUT_STREAM, localisation_dictionary *LD) {
    inter_tree *I = InterpretIndex::get_tree();
    tree_inventory *inv = Synoptic::inv(I);
    TreeLists::sort(inv->table_nodes, Synoptic::category_order);

    inter_package *current_mod = NULL; int mc = 0, first_ext = TRUE;
    inter_ti cat = 1, open_cat = 0;
    for (inter_ti with_cat = 1; with_cat <= 3; with_cat++) {
        inter_package *table_pack;
        LOOP_OVER_INVENTORY_PACKAGES(table_pack, i, inv->table_nodes) {
            inter_package *mod = Synoptic::module_containing(table_pack->package_head);
            if (mod) {
                cat = Metadata::read_optional_numeric(mod, I"^category");
                if (cat == with_cat) {
                    if ((mc == 0) || (mod != current_mod)) {
                        Close block of tables1.2;
                        mc++; current_mod = mod;
                        Open block of tables1.1;
                    }
                    Index this table1.3;
                }
            }
        }
    }
    Close block of tables1.2;
}

§1.1. Open block of tables1.1 = 

    if (cat > 1) {
        if (first_ext) {
            HTML_OPEN("p");
            IndexUtilities::extra_link(OUT, 2);
            if (mc > 1) WRITE("Show tables inside extensions too");
            else WRITE("Show tables inside extensions (there are none in the main text)");
            HTML_CLOSE("p");
            first_ext = FALSE;
        }
        IndexUtilities::extra_div_open(OUT, 2, 1, "e0e0e0");
        HTML_OPEN("p");
        WRITE("<i>%S</i>", Metadata::read_textual(mod, I"^title"));
        HTML_CLOSE("p");
    }
    open_cat = cat;
    HTML::begin_plain_html_table(OUT);

§1.2. Close block of tables1.2 = 

    if (mc > 0) {
        HTML::end_html_table(OUT);
        if (open_cat > 1) IndexUtilities::extra_div_close(OUT, "e0e0e0");
    }

§1.3. The following probably ought to use a multiplication sign rather than a Helvetica-style lower case "x", but life is full of compromises.

Index this table1.3 = 

    HTML::first_html_column_spaced(OUT, 0);
    WRITE("<b>%S</b>", Metadata::read_textual(table_pack, I"^printed_name"));
    int ntc = 0;
    inter_tree_node *D = Inter::Packages::definition(table_pack);
    LOOP_THROUGH_INTER_CHILDREN(C, D) {
        if (C->W.data[ID_IFLD] == PACKAGE_IST) {
            inter_package *entry = Inter::Package::defined_by_frame(C);
            if (Inter::Packages::type(entry) == PackageTypes::get(I, I"_table_contribution")) {
                if (ntc++ > 0) WRITE(" +");
                IndexUtilities::link_package(OUT, entry);
            }
        }
    }
    HTML::next_html_column_spaced(OUT, 0);

    int nc = 0;
    LOOP_THROUGH_INTER_CHILDREN(C, D) {
        if (C->W.data[ID_IFLD] == PACKAGE_IST) {
            inter_package *entry = Inter::Package::defined_by_frame(C);
            if (Inter::Packages::type(entry) == PackageTypes::get(I, I"_table_column_usage"))
                nc++;
        }
    }
    int nr = (int) Metadata::read_numeric(table_pack, I"^rows");
    int nb = (int) Metadata::read_numeric(table_pack, I"^blank_rows");
    int defines = (int) Metadata::read_optional_numeric(table_pack, I"^defines");
    text_stream *for_each = Metadata::read_optional_textual(table_pack, I"^blank_rows_for_each");

    WRITE("<i>");
    HTML_OPEN_WITH("span", "class=\"smaller\"");
    if (defines) {
        WRITE("%d definition%s", nr, (nr == 1)?"":"s");
    } else {
        WRITE("%d column%s x %d row%s", nc, (nc == 1)?"":"s", nr, (nr == 1)?"":"s");
    }
    if (nb > 0) {
        WRITE(" (%d blank", nb);
        if (Str::len(for_each) > 0) WRITE(", one for each %S", for_each);
        WRITE(")");
    }
    HTML_CLOSE("span");
    WRITE("</i>");

    HTML::end_html_row(OUT);

    int col = 0;
    LOOP_THROUGH_INTER_CHILDREN(C, D) {
        if (C->W.data[ID_IFLD] == PACKAGE_IST) {
            inter_package *entry = Inter::Package::defined_by_frame(C);
            if (Inter::Packages::type(entry) == PackageTypes::get(I, I"_table_column_usage")) {
                inter_tree_node *ID = Synoptic::get_definition(entry, I"column_identity");
                inter_symbol *id_s = NULL;
                if (ID->W.data[DATA_CONST_IFLD] == ALIAS_IVAL)
                    id_s = InterSymbolsTables::symbol_from_id(Inter::Packages::scope(entry), ID->W.data[DATA_CONST_IFLD+1]);
                if (id_s == NULL) internal_error("column_identity not an ALIAS_IVAL");
                inter_package *col_pack = Inter::Packages::container(id_s->definition);
                HTML::first_html_column(OUT, 0);
                WRITE("&nbsp;&nbsp;col %d:&nbsp;&nbsp;", col+1);
                Give column details1.3.1;
                HTML::next_html_column(OUT, 0);
                Give column 2 details1.3.2;
                HTML::end_html_row(OUT);
                col++;
            }
        }
    }

§1.3.1. Give column details1.3.1 = 

    text_stream *CW = Metadata::read_optional_textual(col_pack, I"^name");
    if ((defines) && (col == 0)) {
        WRITE("%S", Metadata::read_optional_textual(table_pack, I"^defines_text"));
        int at = (int) Metadata::read_optional_numeric(table_pack, I"^defines_at");
        IndexUtilities::link(OUT, at);
    } else {
        if (defines) WRITE("<i>sets</i> ");
        WRITE("%S&nbsp;", CW);
        TEMPORARY_TEXT(TEMP)
        WRITE_TO(TEMP, "%S", CW);
        if (defines == FALSE) WRITE_TO(TEMP, " entry");
        PasteButtons::paste_text(OUT, TEMP);
        DISCARD_TEXT(TEMP)
    }

§1.3.2. Give column 2 details1.3.2 = 

    if ((defines) && (col == 0)) {
        WRITE("<i>names</i>");
    } else if (defines) {
        WRITE("%S property", Metadata::read_optional_textual(col_pack, I"^contents"));
    } else {
        WRITE("of %S", Metadata::read_optional_textual(col_pack, I"^contents"));
    }