A '''routine''' is a modular unit of a [program].  In Tcl, there is a routine
associated with each available [procedure].  To [eval%|%evaluate] a command,
Tcl uses the first [word] of the command to find the procedure and execute the
associated routine.  Many [Tcl Commands%|%built-in commands] are implemented as
[C] functions.  In the case of a procedure defined by `[proc]`, the primary
function of the routine is to evaluate the body of the procedure.

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