Maximum number of attribute $n in transforms.conf

[CurryPan]

Hello,
the FORMAT option in transforms.conf can use $n to specify the output of each REGEX match.
(https://docs.splunk.com/Documentation/Splunk/latest/Admin/Transformsconf)

FORMAT = <string>
(* snip *)
* FORMAT for index-time extractions:
* Use $n (for example $1, $2, etc) to specify the output of each REGE match.

Is there a hard limit on the maximum number of attribute $n in transforms.conf?

[CurryPan]

There is a hard limit of 65535 imposed by PCRE2 library:

There is no limit to the number of parenthesized subpatterns, but there can be no more than 65535 capturing subpatterns.
(http://www.pcre.org/current/doc/html/pcre2limits.html)