Use " |x " for subfield ind, replacing x1f with " |x",
where x is in [a-z]
   $var =~ s/\x1f[a-z]/ \|$& /g;

Remove leading spaces
   $var =~ s/^ +//;

Remove trailing space characters
   $var =~ s/\s+$//;

Collapse "nonWord-char+space" to "space"
   $var =~ s/\W / /g;

Collapse white space occurrences down to 1 space each
   $var =~ s/\s\s*/ /g;

Convert input string to hexadecimal
   $var =~ s/(.)/sprintf ("%%%X", ord($1))/eg;

Restore formfeed character as passthrough
   $var =~ s/^%C/sprintf("%c", 12)/e;

Convert hex character value to equivalent unsigned char value
   $var =~ s/$hex_char_var/pack("C", hex($hex_char_var))/eg;

Convert to upper case
   $var =~ tr/a-z/A-Z/;

Remove LF at End Of Line
   $var =~ s/\n$//;

Determine how many elements are populated in the array.
In this case each element is 22 chars long.
Loops until encounters empty element. (dependable?)
   $ctr = 0;
   while (not ($array[$idx] =~ /( ){22}/))
   {
     $ctr++;
     $idx++
   }

Fields in $var are separated by " | ".
Remove blank fields.
   $var =~ s/ \|  \| / \| /g;

Fields in $var are separated by " | ".
Remove trailing blank fields.
   $var =~ s/ \| $//;

Condition true if $var contains only digits
   if ($var =~ /^[0-9]+$/) {then true}

True if date in $var is of format nn/nn/nnnn; no extra chars
   if ($var =~ /^\d{2}\/\d{2}\/\d{4}$/) {then true}

Strip high ASCII chars from $var
   $var =~ tr/\x80-\xff//d;

Count occurrences of string represented by "word" (destructive)
$count = ($var =~ s/word//g);

Replace all <...> constructs with "|"
$var =~ s/\<([a-zA-Z0-9\/\=\"\#]+)\>/\|/g;



File-wide substitution from the command line

perl -pi -e's/\#\#\#/   /g' yourfile   # sample substitution pattern