This is done for the next version (still a long time away, so don't ask “when?”).
- ${nnn} is supported, replaces with the respective capture group, or “${nnn}” is there is insufficient capture groups.
- \n (single digit n only) replaces with the respective capture group, or “\n” is there is insufficient capture groups
- $nnn replaces with the respective capture groups. If there is less than 10 capture groups, then $123 will replace with the first capture group, followed by “23”. If there were at least twelve capture groups, then it would be the 12th capture group, followed by “3”
- ${name} replaces with the respective named capture group, or “${name}” if there is no such named capture group. This required 10.13+. Name must start with an ASCII letter, followed by zero or more ASCII letters and numbers.