1 10/17/84  reverse_decat, rvdecat
 2 
 3 Syntax as a command:  rvdecat STRA STRB C
 4 
 5 
 6 Syntax as an active function:  [rvdecat STRA STRB C]
 7 
 8 
 9 Function:  performs the same function as the decat command/active
10 function, but in reverse order.
11 
12 
13 Notes:  The active function returns the "decatenation" of STRA with
14 respect to the last occurrence of STRB in STRA (decat uses the first
15 occurrence).  The value for C is any three-digit bit string expressed
16 as 0 or as 1 characters such as 000,001,...,111.  The last occurrence
17 of STRB found in STRA divides STRA into three parts:  the part prior to
18 STRB, the part matching STRB, and the part following STRB.  Digits of C
19 correspond to these three parts.  The return string contains the parts
20 of STRA whose corresponding bit in C is 1.  The parts are returned in
21 their original order of appearance in STRA.
22    [reverse_decat STRA STRB C]
23 is the same as--
24    [reverse [decat [reverse STRA] [reverse STRB] [reverse C]]]
25 when STRB appears in STRA.  It is also the same as--
26    [decat STRA STRB C]
27 when STRB does not appear in STRA.