I'm trying to to convert an existing PHP Regular Expression match case to apply to a slightly different style of document.

Here's the original style of the document:

**FOODS - TYPE A** 
___________________________________ 
**PRODUCT** 
1) Mi Pueblito Queso Fresco Authentic Mexican Style Fresh Cheese; 
2) La Fe String Cheese 
**CODE** 
Sell by date going back to February 1, 2009 

And the successfully-running PHP Regex match code that only returns "true" if the line is surrounded by asterisks, and stores each side of the "-" as $m[1] and $m[2], respectively.

 if ( preg_match('#^\*\*([^-]+)(?:-(.*))?\*\*$#', $line, $m) ) { 
    // only for **header - subheader** $m[2] is set. 
    if ( isset($m[2]) ) { 
      return array(TYPE_HEADER, array(trim($m[1]), trim($m[2]))); 
    } 
    else { 
      return array(TYPE_KEY, array($m[1])); 
    } 
  } 

So, for line 1: $m[1] = "FOODS" AND $m[2] = "TYPE A"; Line 2 would be skipped; Line 3: $m[1] = "PRODUCT", etc.

The question: How would I re-write the above regex match if the headers did not have the asterisks, but still was all-caps, and was at least 4 characters long? For example:

FOODS - TYPE A 
___________________________________ 
PRODUCT
1) Mi Pueblito Queso Fresco Authentic Mexican Style Fresh Cheese; 
2) La Fe String Cheese 
CODE
Sell by date going back to February 1, 2009 

Thank you.