The token $::| appears in the list of all known magic punctuation variables in PPI::Token::Magic. It's listed in PPI's changelog as a bug fix in January of 2005. It isn't in perlvar or—best I can tell—on this site. Under 5.10, this one-liner: 
perl -e 'use strict; use warnings; print "$::|\n";'

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...produces this output: 

Use of uninitialized value $main:: in concatenation (.) or string at -
+e line 1.
|

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And this: 

my $thingy =  $::|;

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...won't even compile. So whatever it was, it doesn't seem to be magic anymore. What did $::| mean, and when was it in force?

Update: That string doesn't appear to appear in the source for perls 5.4 through 5.10.

cat >~/.brain </dev/the_answer

In reply to What is $::| ? by misterwhipple

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