# PerlIO Namespace containing the following modules: - [`PerlIO::encoding`](PerlIO/encoding.md) — Open a filehandle with a transparent character-set encoding filter. - [`PerlIO::mmap`](PerlIO/mmap.md) — Memory-mapped IO layer opened as `<:mmap`, with a read()/write() fallback when mmap fails. - [`PerlIO::via`](PerlIO/via.md) — Write a PerlIO layer in Perl: open with `:via(MyClass)` and I/O dispatches to your class.