You are right Scott, on some sites there is a robots.txt editor, however my site doesn't have one and I can't figure out how to get it to show up.
I created one manually and it still doesn't show up the Edit Files tab of the Yoast plugin. I had another Robots plugin installed that perhaps commandeered that part of WP or something...?
I also get this entry in the .htaccess portion of the Edit Files page:
“If your .htaccess file were writable, we could do this automatically, but it isn’t so these are the mod_rewrite rules you should have in your .htaccess file.” Then in the box it says, "Options +SymlinksIfOwnerMatch"
My site is old enough I was running Yoast's plugin back before it had the Robots/HTAccess integration I believe also, when he had the separate Robots Meta plugin...
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Yoast if you get time, I'm sure you have dealt with these issues before so link us up to some details for the resolution(s) if you can! Thanks!