1 10/17/84  reverse_search, rvsrh
 2 
 3 Syntax as a command:  rvsrh STRA STRB
 4 
 5 
 6 Syntax as an active function:  rvsrh STRA STRB
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 8 
 9 Function:  performs the same function as the search command/active
10 function, but in reverse order.
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12 
13 Notes:  The active function returns the index (character position) of
14 the last character in STRA that appears in STRB (search returns the
15 first such character).  If no characters of STRA appear in STRB, 0 is
16 returned.
17    [reverse_search STRA STRB]
18 is the same as--
19    [length STRA] - [search [reverse STRA] STRB] + 1
20 when a character of STRB appears in STRA.  It is 0 when a character of
21 STRB does not appear in STRA.