"Backreferences" are references in a search regex to capture groups in the same search regex. The "search regex" is the regex used in the "Find" field of the Find/Replace dialog box. Here is the most common backreference syntax:
Absolute: (group one)...\1
Relative: (group one)(group two)...\-1
Named: (?<name>group)...\k<name>
"Substitutions" are references in a replacement regex to capture groups in the associated search regex. The "replacement regex" is the regex used in the "Replace" field of the Find/Replace dialog box. Here is the most common substitution syntax:
Absolute: $1
Named: $+{name}
The formats \1
, \-1
, and $n
are limited single-digit numbers. In order to positionally reference a capture group greater than nine, use the following syntax instead:
Backreference: (group one)...(group ten)...\g{10}
Substitution: ${10}