def _validate_record_field_positions_global(record):
all_fields = []<EOL>for tag, fields in list(record.items()):<EOL><INDENT>previous_field_position_global = -<NUM_LIT:1><EOL>for field in fields:<EOL><INDENT>if field[<NUM_LIT:4>] < previous_field_position_global:<EOL><INDENT>return ("<STR_LIT>" %<EOL>tag)<EOL><DEDENT>previous_field_position_global = field[<NUM_LIT:4>]<EOL>if field[<NUM_LIT:4>] in all_fields:<EOL><INDENT>return ("<STR_LIT>" %<EOL>(field[<NUM_LIT:4>], tag))<EOL><DEDENT><DEDENT><DEDENT>
Check if the global field positions in the record are valid.

I.e., no duplicate global field positions and local field positions in the
list of fields are ascending.

:param record: the record data structure
:return: the first error found as a string or None if no error was found