/6(?:011|5[0-9]{2})[ \-,]?[0-9]{4}[ \-,]?[0-9]{4}[ \-,]?[0-9]{4}/g
#+ number only field starts with 6011 or 65
6011079538309558
6535944365696599
#+ number string
<sometag1>somedata</sometag1><sometag2><num>6011079538309558</num>
<sometag1>somedata</sometag1><sometag2><num>6535944365696599</num>
#+ with spaces
<sometag1>somedata</sometag1><sometag2><num> 6011 0795 3830 9558</num>
<sometag1>somedata</sometag1><sometag2><num>6535 9443 6569 6599</num>
#+ with dash
<sometag1>somedata</sometag1><sometag2><num> 6011-0795-3830-9558</num>
<sometag1>somedata</sometag1><sometag2><num>6535-9443-6569-6599</num>
#+ with comma
<sometag1>somedata</sometag1><sometag2><num> ,,6011,0795,3830,9558</num>
<sometag1>somedata</sometag1><sometag2><num>6535,9443,6569,6599</num>
#+ bigger numbers
<sometag1>somedata</sometag1><sometag2><num>3449906011079538309558565566</num>
<sometag1>somedata</sometag1><sometag2><num>3449653594436569659965566</num>
#+ bigger numbers with space
<sometag1>somedata</sometag1><sometag2><num>3449 906011 0795 3830 955893565 566</num>
<sometag1>somedata</sometag1><sometag2><num>3449 9506535 9443 6569 6599254654665 566</num>
#- SHOULD NOT MATCH with other starting numbers
32042877059846
37592951984335
39152870324798
<sometag1>somedata</sometag1><sometag2><num>3549 900969 593565 566</num>
