Thanks for the reply! I've taken the time between posting and your response to dive much deeper into XML than I have before. What I think I want can be accomplished with XPath. I believe your solution does something similar.

Here's what I came up with so far. Please chime in on my approach. First, though, I have to clarify that my original XML file example was not 100% representative of my structure. It looks more like this

<a>
    <b id='id1' type="1"/>
    <b id='id2' type="1.5"/>
    <b id='id3' type="2"/>
    <c id='id4'/>
    <b id='id5' type="3"/>
</a>
[download]

Then, I can use XML::XPath to get what I want using the following

use warnings;
use strict;
use XML::XPath;
use XML::XPath::XMLParser;

my $xmlFile = "try.xml";

# create an object to parse the file and field XPath queries
my $xpath = XML::XPath->new(filename => $xmlFile) || die "Problem: $!\
+n";

# look for the preceding sibling node to the one in question
my $nodeset = $xpath->find('//*[@id=' . "'id4']/preceding-sibling::*[1
+]");
foreach my $node ( $nodeset->get_nodelist ) {
    print XML::XPath::XMLParser::as_string( $node ) . "\n";
}
[download]