$string="OWN - NLM STAT- Publisher DA - 20091005  AU - Gannon AM AU - Turner EC AU - Reid HM AU - Kinsella BT  AU- XYZ AD - UCD School of Biomolecular and Biomedical Sciences";

OWN- NLM
STAT- Publisher 
DA - 20091005
AU- Gannon AM Turner EC Kinsella BT XYZ
AD - UCD School of Biomolecular and Biomedical Sciences

$srting=~/OWN-(.*)AU(.*)/g;

#!/usr/bin/perl -w
use strict;
 
$_ = "OWN - NLM "
   . "STAT- Publisher "
   . "DA - 20091005 "
   . "AU - Gannon AM "
   . "AU - Turner EC "
   . "AU - Reid HM "
   . "AU - Kinsella BT "
   . "AU- XYZ "
   . "AD - UCD School of Biomolecular and Biomedical Sciences";
print;
print "\n";
#Parse the above string into key-value pairs.
s/([A-Z]+\s*)-/###$1###/g;
#Put the resulting substrings into a list
my @list = [];
@list = split /\s*###/;
 
#Remove leading and trailing spaces from each element
foreach my $i (@list) {
    $i =~ s/^\s+//;
    $i =~ s/\s+$//;
}
 
#The first element is empty. Remove it with shift.
shift @list;
#Here's what the list contains now
for (0..$#list) {
    print "Element $_: $list[$_]\n";
}

#!/usr/bin/perl -w
#ParseStringCreateHash.pl
use strict;
$_ = "OWN - NLM STAT- Publisher DA - 20091005  AU - Gannon AM AU - Turner EC AU - Reid HM AU - Kinsella BT  AU- XYZ AD - UCD School of Biomolecular and Biomedical Sciences";
print "\n";
#Parse the above string into key-value pairs.
s/([A-Z]+\s*)-/###$1###/g;
#Put the resulting substrings into a array
my @array = [];
@array = split /\s*###/;
 
#Remove leading and trailing spaces from each element
foreach my $i (@array) {
    $i =~ s/^\s+//;
    $i =~ s/\s+$//;
}
 
#The first element is empty. Remove it with shift.
shift @array;
#Here's what the array contains now
print "Here's what the array contains now:\n";
for (0..$#array) {
    print "Element $_: $array[$_]\n";
}
#Create a hash from the above array
my %hash = ();
for (0..$#array) {
    if ($_%2 eq 0) { #$_ is even
        #Array element represents a hash key
        unless (exists $hash{$array[$_]}) {
            $hash{$array[$_]} .= "";
    }   }
    else { #$_ is odd
        #Array element[$_] represents part of value associated with previous element-key
        $hash{$array[$_ - 1]} .= "$array[$_] "
    };
}
 
print "\nHash keys and values separated by '-' :\n";
for (keys %hash) {
    print "$_ - $hash{$_}\n";
}

$str=" AB  - Thromboxane plays an essential role in hemostasis, regulating platelet aggregation and vessel tone. TP - beta- isoforms that are transcriptionally regulated by distinct  Prm1 and Prm3, respectively";

AB -  Thromboxane plays an essential role in hemostasis, regulating platelet aggregation and vessel tone. TP - beta- isoforms that are transcriptionally regulated by distinct  Prm1 and Prm3, respectively.

 TP - beta- isoforms that are transcriptionally regulated by distinct  Prm1 and Prm3, respectively
AB - Thromboxane plays an essential role in hemostasis, regulating platelet aggregation and vessel tone

AB - Thromboxane plays an essential role in hemostasis, regulating platelet aggregation and vessel tone. TP - beta- isoforms that are transcriptionally regulated by distinct  Prm1 and Prm3, respectively.

<ID tags>
elements: AB AD TP etc. 
elements: <id string>
<id string>
elements: any character that is not an id tag.
<School Tags>
elements: AU <school info>etc
<school info>
elemsnts: any character that is not a School Tag

#RULE 1:
# Every substring consisting of capital letters followed by 
# a hyphen (-) represents a key and whatever follows before the 
# next substring consisting of capital letters followed by 
# a hyphen is the value associated with that key.
$str1="OWN - NLM STAT- Publisher DA - 20091005  AU - Gannon AM AU - Turner EC AU - Reid HM AU - Kinsella BT  AU- XYZ AD - UCD School of Biomolecular and Biomedical Sciences"; 
#
#RULE 2:
# A substring consisting of capital letters followed by a hyphen - 
# represents a key only if it occurs at the beginning of a line. 
# It may (or must?) be preceded by a space which we will 
# remove when we put the key in the hash. 
# Whatever follows, including substrings of capital letters 
# followed by a hyphen, up until the end of the line 
# (indicated by a newline character?) is the value associated 
# with that key.
$str2=" AB  - Thromboxane plays an essential role in hemostasis, regulating platelet aggregation and vessel tone. TP - beta- isoforms that are transcriptionally regulated by distinct  Prm1 and Prm3, respectively";