Add a NATIONAL section to TODO

TODO

@@ -65,6 +65,7 @@ Mostly implemented
 
 3.3 add checks 
 
+
 4 Optimization
 
 4.1 More inlining of run-time functions
@@ -175,6 +176,7 @@ This function is relative often called in production systems and
 re-calculates the picture on runtime, which the compiler already
 did - pass this information along with the call.
 
+
 5 Debugging support
 
 5.1 Data access method
@@ -197,3 +199,69 @@ GnuCOBOL 4 provides this quite complete at runtime, too.
 Yes, we should, for now: refer to the GnuCOBOL Programmer's Guide
 https://sourceforge.net/p/gnucobol/code/HEAD/tree/external-doc/guide/
 
+
+7 NATIONAL support
+
+Finish implementation of NATIONAL support.
+
+This implies to take care - among other things - of the many TODOs in the following functions:
+
+* tree.c
+- cb_tree_category (CB_TAG_FIELD)
+- cb_tree_type (CB_USAGE_NATIONAL)
+- cb_build_picture ('N')
+
+* parser.y
+- prepare_default_collation
+- program_coll_sequence_values
+- alphabet_type_national
+- symbolic_characters_clause
+- class_name_clause
+- coll_sequence_values
+- usage_screen_report
+- usage
+- class_value
+
+* scanner.l
+- N[''""]
+- NC[''""]
+- U[''""]
+- error_literal
+- read_literal
+- scan_x
+
+* typeck.c
+- cb_emit_sort_init (nat_col)
+
+* field.c
+- validate_any_length_item
+
+* codegen.c
+- output_alphabet_name_definition
+
+* reserved.c
+- function_list (CHAR-NATIONAL, EXCEPTION-FILE-N, EXCEPTION-LOCATION-N, NATIONAL-OF)
+
+* intrinsics.c
+- cob_check_numval_f
+- numval
+- cob_check_numval
+- cob_intr_bit_of
+- cob_intr_hex_of
+- cob_intr_numval_f
+- cob_intr_char_national
+- cob_intr_display_of
+- cob_intr_exception_file_n
+- cob_intr_exception_location_n
+- cob_intr_national_of
+
+* common.c
+- cob_cmp
+
+* fileio.c
+- indexed_open
+
+* mlio.c
+- set_xml_text
+- xml_generate
+- cob_json_generate_new