The APEX_DATA_PARSER package uses the following constants.

subtype t_file_type is pls_integer range 1..4;
c_file_type_xlsx              constant t_file_type      := 1;
c_file_type_csv               constant t_file_type      := 2;
c_file_type_xml               constant t_file_type      := 3;
c_file_type_json              constant t_file_type      := 4;