$ cat t
STRING1
STRING2
STRING3
STRING4


## perl script
print "....Some---Header....... ## Must preserve all the header tags\n";
open ( STRINGS, "</temp/tmp/t") or die ("***Error- Couldn't open file: C:/temp/tmp/t, $!\n");
while ( <STRINGS> ) {
  chomp;
  print "<SignalPreference>\n";
  print "        ...   #Must preserve this part as it is\n";
  print "        <SignalName>$_</SignalName>\n";
  print "        ...  #Must preserve this part as it is\n";
  print "</SignalPreference>\n";
  print "\n";
  print "......Some formatting text.......   ### must Preserve this as it is\n";
}
close STRINGS;
print "....Some footer text......  ### Must preserve this as it is.\n";


$ test.pl
....Some---Header....... ## Must preserve all the header tags
<SignalPreference>
        ...   #Must preserve this part as it is
        <SignalName>STRING1</SignalName>
        ...  #Must preserve this part as it is
</SignalPreference>

......Some formatting text.......   ### must Preserve this as it is
<SignalPreference>
        ...   #Must preserve this part as it is
        <SignalName>STRING2</SignalName>
        ...  #Must preserve this part as it is
</SignalPreference>

......Some formatting text.......   ### must Preserve this as it is
<SignalPreference>
        ...   #Must preserve this part as it is
        <SignalName>STRING3</SignalName>
        ...  #Must preserve this part as it is
</SignalPreference>

......Some formatting text.......   ### must Preserve this as it is
<SignalPreference>
        ...   #Must preserve this part as it is
        <SignalName>STRING4</SignalName>
        ...  #Must preserve this part as it is
</SignalPreference>

......Some formatting text.......   ### must Preserve this as it is
....Some footer text......  ### Must preserve this as it is.