$re = '/(abc|bcd|cde|def|efg|fgh|ghi|hij|ijk|jkl|klm|lmn|mno|nop|opq|pqr|qrs|rst|stu|tuv|uvw|vwx|wxy|xyz)(19\d{2}|20[01]\d)(10{1,3}|[25]0{1,2})\d/m';
$str = 'abc1500100
mno16001001
xyz180010000
opq2001101
opq1901101
opq2019101
opq20192001
opq20105001
opq197010000
opq2020101
abd1888101
abc1499101
abc2021101
abc2020201';
preg_match_all($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