The tag is present in Lintian version 2.104.244. That is the most recent version we know about.
/etc/init.d script has an LSB keyword section starting
### BEGIN INIT INFO but either has no matching
INIT INFO or has lines between those two markers that are not
comments. The line number given is the first line that doesn't look like
part of an LSB keyword section. There must be an end marker after all
the keyword settings and there must not be any lines between those
markers that do not begin with
Refer to https://wiki.debian.org/LSBInitScripts for details.