sub mkrange {
  my ($r1, $r2) = @_;
  return sub { /$r1/../$r2/ };
}

my $range1 = mkrange(qr/FIRST/, qr/SECOND/);
my $range2 = mkrange(qr/THIRD/, qr/FOURTH/);

while (<DATA>) {
  if ( $range1->() ) {
    print "R1: $_";
  }
  if ( $range2->() ) {
    print "R2: $_";
  }
}
__END__
junk
FIRST
1
2
3
SECOND
junk
THIRD
4
5
6
FOURTH
junk
[download]

Within the same block, .. conditionX associates with the nearest condition1 .. condition2 lexically above it. So in:

if (cond1 .. cond2) { if ( .. condA) { } }
if (      .. cond3) { }
if (cond4 .. cond5) { if (condB .. condC) }
if (      .. cond6) { }
[download]

.. cond3 would associate with cond1 .. cond2

.. condA would not, because its in a different block (it would be an orphan)

.. cond6 would associate with cond4 .. cond5 (it would not "see" condB .. condC because that is in a different block)

In terms of parsing, the handler for .. conditionX would search backwards until it found a conditionV .. conditionW or the beginning of the block. Then the conditionV .. conditionW would be "informed" of the .. conditionX

(Updated to add paragraph about parsing)