Just want to point out that this will cause problems (i.e. an infinite loop) if you hit EOF (end of file) here:

        $line = <$FILE>;
        until ( $line =~ /^c/ or $line =~ /^mt?\d+/ ) {
            ...
            $line = <$FILE>;
        }
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I like to write my parsing loops so that I only read lines in one place - like in the outer while statement. Then I only have to check for EOF in one place.

Also, here's a simpler way to look at the problem. You have three kinds of lines:

• Comments (m/^c/)
• Initial m-block lines (m/^m/)
• Continuation lines (m/^\s/)

You can write a simple "event processing" loop as follows:

while (<$FILE>) {
  if (m/^m/) { ... }
  elsif (m/^\s/) { ... }
  elsif (m/^c/) { ... }
  else { die "whoops - didn't expect: $_" }
}
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Now you just have to work out what to do in each of the three cases. My suggestion is to create a variable to represent the current m-block being recognized. The actions for each type of line would go something like this:

• Continuation line: add the line to the current block.
• Initial m-block line: process the current block, reset it and then add the line to the current block
• Comments: process the current block and reset it

Also, at the end of the loop you'll have to see if there's a block that needs to be processed.