This Tcl command is obsolete and is supported only for
backward compatibility.  At some point in the future it may be
removed entirely.  You should use the [switch] command instead.

----

Fair enough, but you can't erase this command from history.  
In fact the command is valid in current Tcl!

Until recently
there was a link to http://purl.org/tcl/home/man/tcl8.4/TclCmd/case.htm
but that link is dead now.  It would be fine if someone could restore this
piece of documentation.  

Suppose you have some old code using this command, and as
a good Tcl citizen you want to follow the advice above.  But how
are you supposed to rewrite the line and use switch instead 
if there is no specification
to be found of the old command?

Note that it is not as simple as substituting "case" by "'switch"...
----
[RS] 2005-12-04 - Remember that Tcl has quite helpful error messages. I tried this:
 % case
 wrong # args: should be "case string ?in? patList body ... ?default body?"
 % case foo in {a* b*} {puts 1} {c* d*} {puts 2} {e* f*} {puts 3} 
 3
So it appears as if elements in ''patList'' are matched in [glob] style :) Compare this to the ''case'' control structure in Unix shells, e.g. in [bash]:
    case word in [ [(] pattern [ | pattern ] ... ) list  ;;  ]
    ... esac
           A case command first expands  word,  and  tries  to
           match  it  against  each pattern in turn, using the
           same matching rules as for pathname expansion  (see
           Pathname  Expansion below).  When a match is found,
           the corresponding  list  is  executed.   After  the
           first  match,  no subsequent matches are attempted.
           The exit status is  zero  if  no  pattern  matches.
           Otherwise,  it  is the exit status of the last com-
           mand executed in list.
with the bad voodoo of using ";;" as case separator, and ''esac'' as end marker...