Something along the lines of:

use feature ":5.14";
use warnings FATAL => qw(all);
use strict;

my ($c, $s) = (0, '');
for(split /\n/, << 'END') 
LABEL#00001
         
         MVC   SYMBOL+2(4),X.PDES_KEY+2                               
+          
         MVC   SYMB_ART,=C'XSEQ'              //line comments         
+                         
                                                                      
+          
         F$SFH SELECT,LISTING,                                        
+ *        
               DESKART=SYMB_ART,                                      
+ *        
               DESKWERT=SYMBOL,                                       
+ *        
               MARKTCODE=L#MACF                                       
+          
         BNE   F03#000                     //line comments
END

 {if (length > 71 and substr($_, 71, 1) eq '*') # Detect continuation
   {s/\A\s*// if $c == 1;                       # Strip leading space 
+in continuation  
    s/\s*\*\s*\Z//;                             # Strip trailing space
    ($s, $c) = (($c ? $s : '').$_, 1);          # Concatenate or resta
+rt depending on continuation state
   }
  else
   {s/\A\s*// if $c == 1;                       # Strip leading spaces
+ in continuation
    say "$s$_";                                 # Write completed stat
+ement
    ($s, $c) = ('', 0);                         # Restart
   }
 }

[download]

Produces

LABEL#00001
         
         MVC   SYMBOL+2(4),X.PDES_KEY+2                               
+          
         MVC   SYMB_ART,=C'XSEQ'              //line comments         
+                         
                                                                      
+          
         F$SFH SELECT,LISTING,DESKART=SYMB_ART,DESKWERT=SYMBOL,MARKTCO
+DE=L#MACF                                                 
         BNE   F03#000                     //line comments

[download]

In reply to Re: how to append 2 lines by philiprbrenan
in thread how to append 2 lines by suno

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