$re = '/(?:\s|\\\\n\\\\n)*(?<subject>\S+(?:\s[IVX]+\.?)?)(?:\s|\\\\n\\\\n)+(?<teacher>\S+)(?:\s|\\\\n\\\\n)+(?<room>\S+)(?:\s|\\\\n\\\\n)*/';
$str = 'TSG MUM \\n\\nBS06-312
RQWE. FKB \\n\\nBS06-204
NM. JAK \\n\\nBS06-E05
DB. FKB \\n\\nBS06-312
IGT. resetk \\n\\nWender.
ENG I. \\n\\nWEHN BS06-E06 \\n\\nENG II \\n\\nFLEM BS06-203
ITSI. MUM \\n\\nBS06-E02
PQT. RIE \\n\\nBS11-QCR PQT \\n\\nMARK BS11-QCR \\n\\nPQT FIS \\n\\nBS11-QCR
INC FEY \\n\\nBS06-309
ABS. DOE \\n\\nBS06 ABS \\n\\nVOG BS06 \\n\\nABS HEI \\n\\nBS06 ABS \\n\\nMOR BS06 \\n\\nABS REM \\n\\nBS06 ABS \\n\\nDEI BS06 \\n\\nABS THA \\n\\nBS06
ENG III. \\n\\nGLIT BS06-209 \\n\\nENG II \\n\\nWANN BS06-208';
preg_match_all($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