The behaviour I see, on "perl, v5.8.8 built for MSWin32-x86-multi-thread" is not consistent with the documentation the OP posted. 
> perl -e "my @y;$y[3]=undef; show(@y); x(@y);show(@y);sub show{my $co
+unt=0;print $count++, qq[ : $_;\n] for @_;print qq[----\n\n]};  sub x
+{ @_[3,4,5,6,8]=(3,4,5,6,939);show(@_)}"

--output--
0 : ;
1 : ;
2 : ;
3 : ;
----

0 : ;
1 : ;
2 : ;
3 : 3;
4 : 4;
5 : 5;
6 : 6;
7 : ;
8 : 939;
----

0 : ;
1 : ;
2 : ;
3 : 3;
----

[download]
I would document the observed behaviour as :
Array elements are NOT created. Existing elements (which were EXPLICITLY created) will retain modifification in the sub.

     "An undefined problem has an infinite number of solutions." - Robert A. Humphrey         "If you're not part of the solution, you're part of the precipitate." - Henry J. Tillman

In reply to Re: perlsub question.. by NetWallah
in thread perlsub question.. by Anonymous Monk

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