The standard library text_base_io package is implemented in src/lib/std/src/io/text-base-io.pkg via invocation of base_io_g from src/lib/std/src/io/base-io-g.pkg.
The text_base_io package is used by file_g from src/lib/std/src/io/file-g.pkg.
It is also used by the file, when and packages, and by read_eval_print_loop_g from src/lib/compiler/toplevel/interact/read-eval-print-loop-g.pkg.
The above information is manually maintained and may contain errors.
Base_Io?