• The Tcl I/O system as seen by a driver (channel type) — A HOWTO Guide for writing new channel types.
• The interaction between the I/O subsystem and the notifier — Describes how the internal core modules 'notifier' and 'I/O' interact for the generation and handling of fileevents.
• HOWTO: Make an Extension Thread-Safe — This document describes the basic constructs for making an application thread-safe