$re = '/(?s)^SCHEDULE(?:.(?!^END$))*?#\/[^\r\n]*E\r?\n(?:(?!^$).)*?[ \t]*NOP$.*?^END$/m';
$str = '
SCHEDULE MASTERAGENTS#KA0HM00_LEASE
DESCRIPTION "Added by composer."
:
CLA0HDST01#/KA0H/KA0HM00_LEASE/KA0HM010_LEASE_AFT
FOLLOWS KA0HM003_LEASE
FOLLOWS KA0HM007_LEASE
CLA0HDST01#/KA0H/KA0HM00_LEASE/KA0HM006_LEASE
FOLLOWS KA0HM004_LEASA
NOP
MASTERAGENTS#/KA0H/KA0HM00_LEASE/KA0HM00SLEASE
CLA0HDST01#/KA0H/KA0HM00_LEASE/KA0HM003_LEASE
CLA0HDST01#/KA0H/KA0HM00_LEASE/KA0HM002_LEASE
FOLLOWS KA0HM001_LEASE
CLA0HDST01#/KA0H/KA0HM00_LEASE/KA0HM001_LEASE
FOLLOWS KA0HM00S_LEASE
MASTERAGENTS#/KA0H/KA0HM00_LEASE/KA0HM00E_LEASE
FOLLOWS KA0HM010_LEASE_AFT
CLA0HDST01#/KA0H/KA0HM00_LEASE/KA0HM004_LEASE
FOLLOWS KA0HM002_LEASE
CLA0HDST01#/KA0H/KA0HM00_LEASE/KA0HM009_LEASE
FOLLOWS KA0HM004_LEASE
END
';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php