Most of the people ( especially php users) know of the tag cv-pls. I got to know about this tag from the starred conversation in PHP chat room. So i don't think so it would be there forever. There was a link to this gist which explained what it was created for?
This is a nice approach to keep the content of question relating to
php clean on stack overflow, but for all the new people (like me ;) ) who would see this tag for the first time, will surely try to look for it's wiki page on SO, which currently doesn't exists.
So, a request to create a tag wiki page/info page for this tag, as it would be appropriate to keep all the SO related info on SO itself, currently this info seems to be scattered (as in this case, a gist explains a functionality of a process on SO). We can atleast copy-paste the text from the gist to the tag wiki page.
Such kind of things will happen, and we can't stop it, but atleast minimize those, and keep SO environment clean and complete by itself.
One more suggestion
As this is not a compete tag by itself, it's something that got created from the php community on SO, got famous via chat, I suggest to create a separate feature that would support such kind of tags. I envisage, there would be more such tags coming in future.