The string contained in $_ is being joined to the string in the last element of @pdbString This code could also be written as: 
$pdbString[@pdbString - 1] .= $_;

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or 
$pdbString[-1] .= $_;

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Which I find simpler to read (negative index references the array starting from the end).

In reply to Re^3: Problems with Variable Scope in Perl by ruzam
in thread Problems with Variable Scope in Perl by InfoSeeker

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