#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11145686
use warnings;

open my $fh, '<', \<<END or die; # FIXME for testing
first junk line then a blank line

   another junk line
fieldname1,fieldname2
value1,value2
more,body
and,still
more,body
END

do { local $/ = "fieldname"; <$fh> };  # read through "fieldname"
my $header_line = "fieldname" . <$fh>; # complete the line

print "header: $header_line";
while( <$fh> ) # FIXME for testing
  {
  print "  body: $_";
  }

##</code><code>##

header: fieldname1,fieldname2
  body: value1,value2
  body: more,body
  body: and,still
  body: more,body