...
architecture generations of your_entity is
-- make component declaration(s) for structural here
-- make signal declaration(s) here
-- make other declaration(s) here
begin
outer(row)_generate_label : for row_index in row_width_start to row_width_stop generate
begin
inner(column)_generate_label : for column_index in column_width_start to column_width_stop generate
-- make possible declarations here
begin
-- code for unit here (behavioural or structural)
end generate inner(column)_generate_label;
end generate outer(row)_generate_label;
end architecture generations;