pattern

The string match and glob commands test whether strings match a "pattern", with "*" and "?" as notable wildcard characters.

Arguably, a regular expression (as matched by regexp) is also a pattern, though a much more complex one.

In the context of general programming, "pattern" often means "Design Pattern" (as in Design Patterns by Gamma, Helm, Johnson, and Vlissides).

See

• Design patterns in Tcl
• Incr Tcl Design Patterns
• The iterator design pattern
• The observer design pattern
• Prototype Pattern in Tcl
• Snit design patterns
• Visitor Pattern