Browsers without RSS support also see version/revision information - Guest or not.
On the screen in Chrome on localhost:
http://localhost/YaBBtests/test_strict/Build_1926/cgi-bin/yabb2/YaBB.pl en-us Build 1926 Up Sun, 14 Jan 2018 00:42:08 GMT http://blogs.law.harvard.edu/tech/rss YaBB 2.7.00 Revision: 1928 30 http://localhost/YaBBtests/test_strict/Build_1926/cgi-bin/yabb2/YaBB.pl?num=1509458567/0#0 Build 1926 Up/General Board http://localhost/YaBBtests/test_strict/Build_1926/cgi-bin/yabb2/YaBB.pl?num=1509458567/0#0 (Administrator) Tue, 31 Oct 2017 14:02:47 GMT Welcome to your new YaBB 2.7.00 forum.<br /><br />The YaBB team would like to thank you for choosing Yet another Bulletin Board for your forum needs. We pride ourselves on the cost (FREE), the features, and the security. Visit <a href="http://www.yabbforum.com" target="_blank">http://www.yabbforum.com</a> to view the latest development information, read YaBB news, and participate in community discussions.<br /><br />Make sure you login to your new forum as an administrator and visit the Admin Center. From there, you can maintain your forum. You'll want to look at all of the settings, membergroups, categories/boards, and security options to make sure they are set properly according to your needs.
The ONLY WAY currently to disable this is to go into Sources/Sublist.pm and actually comment out
'RSSboard' => 'RSS.pm&rss_board',
AND
'RSSrecent' => 'RSS.pm&rss_recent',
But then, anybody looking at actual urls knows the urls and the Revision number means nothing unless you actually are comparing revisions.
And again, this is NOT a new problem - this is a Chrome problem.