A regex in Notepad++ may have as many capture groups as desired.
(one)(two)(three)...(nine)(more than nine groups!)...
Anonymous capture groups use the standard syntax:
(group)
Named capture groups may use either of following syntax formats:
(?<name>group)
(?'name'group)
Anonymous and named capture groups may be mixed in any order:
(anonymous)(?<name>named)(anonymous)
Capture groups are numbered starting from 1
based on the order of their opening parenthesis', regardless of nesting:
((group 2) group 1)
Note that named groups are included in the numbering:
(group 1)(?<name>group 2)(group 3)