in reply to nested reg ex over multiple lines

Does this do what you want? 

use strict;
use warnings;

my $content = do { local $/; <DATA> };

while ($content =~ m/^(CAL.+?\((\w+)\).*?})/msg){
  print "1= $1\n\n";
  print "2= $2\n\n";
}

__DATA__
CALCON(test1)
{
  TYPE(U8)
  FEATURE(DCOM)
  NAM(stmin)
  LABEL(Min seperation time between CFs)
  MIN(0)
  MAX(127)
  UNITS(ms)  
}

CALCON(test2)
{
  TYPE(U16)
  FEATURE(DCOM)
  NAM(dcomc_sestmr_timeout)
  LABEL(DCOM Session Timer Timeout)
  MIN(0)
  MAX(65535)
  UNITS(ms)
}
__END__
1= CALCON(test1)
{
  TYPE(U8)
  FEATURE(DCOM)
  NAM(stmin)
  LABEL(Min seperation time between CFs)
  MIN(0)
  MAX(127)
  UNITS(ms)  
}

2= test1

1= CALCON(test2)
{
  TYPE(U16)
  FEATURE(DCOM)
  NAM(dcomc_sestmr_timeout)
  LABEL(DCOM Session Timer Timeout)
  MIN(0)
  MAX(65535)
  UNITS(ms)
}

2= test2

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Note the two ? modifiers in the regex (after + and *) that prevent greedy matching. Without them, your matches would be longer than you want.

the lowliest monk

In Section Seekers of Perl Wisdom