$re = '/^SCHEDULE\b.*(?:\n(?!(?:.*#\/.*E|END)$).*)*\r?\n.*#\/.*E\r?\n[^\S\r\n]*NOP(?:\r?\n(?!END$).*)*\r?\nEND$/m';
$str = 'SCHEDULE MANAGER_XA#KAAABBBR
DESCRIPTION "Added by default."
ON RUNCYCLE KAAABBBR VALIDTO 09/24/2021 $RCG KAAABBBR
:
S89AAAABBB1#/XAAA/XCCCDDDD/KA0EG014
FOLLOWS KABBBCCC3
S89AAAABBB1#/XAAA/XCCCDDDD/KAHHHTTTTTE
NOP
FOLLOWS KABBBCCC3
S89AAAABBB1#/XAAA/XCCCDDDD/KAHHHTTTTTS
NOP
FOLLOWS MANAGER_XA#KZZZDDDD.KGGGHHHHHE
END
SCHEDULE MANAGER_XA#KBBBCCCR
DESCRIPTION "Added by default."
ON RUNCYCLE KAAABBBR VALIDTO 09/24/2021 $RCG KBBBCCCR
:
S89AAAABBB1#/XBBB/XCCCDDDD/KA0EG014
FOLLOWS KABBBCCC3
S89AAAABBB1#/XBBB/XCCCDDDD/KAHHHTTTE
FOLLOWS KABBBCCC3
S89AAAABBB1#/XBBB/XCCCDDDD/KAHHHTTTTTS
NOP
FOLLOWS MANAGER_XA#KZZZDDDD.KGGGHHHHHE
END';
preg_match_all($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