A "trick" for reading reguarly formated material like this is to change the input seperator to the header string for each block. Consider:

use strict;
use warnings;

$/ = '0AVERAGE COMPOSITION IN PINS.';

while (<DATA>) {
    next if ! /EID:     Pu-238/;
    
    chomp;
    print "$/$_";
}


__DATA__

[download]
0AVERAGE COMPOSITION IN PINS.  NUMBER DENSITIES IN 1.0E+24/CM3,  WT% P
+ER MASS INITIAL HEAVY ISOTOPES.
 ----------------------------  FOR BA-ELEMENTS WITH EID>99100, WT% IS 
+THE PERCENTAGE LEFT (FRACTION).
0 EID:     Cm-243
  ND : 8.7352E-08
      0
      0  3822
      0  3278     0
      0  3260     0   +++
      0  3242     0   +++   +++
      0  3157     0     0     0   +++
      0  3096     0     0     0   +++   +++
      0  3170     0     0     0     0     0     0
      0  3772  3170  3096  3157  3242  3260  3278  3822*
      0     0     0     0     0     0     0     0     0     0
1GE 12 Bundle VOID=0%                                                 
+ >> PHOENUT /1.2.8   / << CORE MASTER
    9  COMPOS                      CASE= 1 RP=  5 V= 2.9 CO= 0 B= 3307
+ 2007-01-30  13.38.50  Page 668  Job0000
 
 
0AVERAGE COMPOSITION IN PINS.  NUMBER DENSITIES IN 1.0E+24/CM3,  WT% P
+ER MASS INITIAL HEAVY ISOTOPES.
 ----------------------------  FOR BA-ELEMENTS WITH EID>99100, WT% IS 
+THE PERCENTAGE LEFT (FRACTION).
0 EID:     Pu-238
  ND : 7.0913E-06
      1
      1  3667
      0  3283     0
      0  3266     0   +++
      0  3250     0   +++   +++
      0  3192     0     0     0   +++
      0  3151     0     0     0   +++   +++
      0  3204     0     0     0     0     0     0
      1  3630  3204  3151  3192  3250  3266  3283  3667*
      1     1     0     0     0     0     0     0     1     1
1GE 12 Bundle VOID=0%                                                 
+ >> PHOENUT /1.2.8   / << CORE MASTER
    9  COMPOS                      CASE= 1 RP=  5 V= 2.9 CO= 0 B= 3307
+ 2007-01-30  13.38.50  Page 669  Job0000

[download]

Prints:

0AVERAGE COMPOSITION IN PINS.  NUMBER DENSITIES IN 1.0E+24/CM3,  WT% P
+ER MASS INITIAL HEAVY ISOTOPES.
 ----------------------------  FOR BA-ELEMENTS WITH EID>99100, WT% IS 
+THE PERCENTAGE LEFT (FRACTION).
0 EID:     Pu-238
  ND : 7.0913E-06
      1
      1  3667
      0  3283     0
      0  3266     0   +++
      0  3250     0   +++   +++
      0  3192     0     0     0   +++
      0  3151     0     0     0   +++   +++
      0  3204     0     0     0     0     0     0
      1  3630  3204  3151  3192  3250  3266  3283  3667*
      1     1     0     0     0     0     0     0     1     1
1GE 12 Bundle VOID=0%                                                 
+ >> PHOENUT /1.2.8   / << CORE MASTER
    9  COMPOS                      CASE= 1 RP=  5 V= 2.9 CO= 0 B= 3307
+ 2007-01-30  13.38.50  Page 669  Job0000

[download]
DWIM is Perl's answer to Gödel

In reply to Re: REGEX on multiple lines by GrandFather
in thread REGEX on multiple lines by igotlongestname

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