Attempting to complete a DBC edit and having a bit of an issue

ownedcore.  com/forums/news/shared/445816-piercing-mists.html

In this post, it shows 2 different dbc edits, within the first 3 screenshots.

The first 2 SS are spell edits and where easy enough to complete, editing flags etc

The third screenshot is the one I am having issues completing. It involves hidden units. From the looks of it, their is a carousel murloc at that location but it is not visible under normal circumstances.

From what I understand, it should be another flag, similar to unlocking hidden aura's etc, I attempted to find this flag in several different DBC files to no avail.

The file I am focusing on is vehicle.dbc, though I am not sure if that is the ideal location.

at this point, I was hoping someone could point me in the right direction, as to where an object/npc/unit flag would be located, that distinguishes it's ability to be seen, targeted, etc

Also, if someone could give a rundown of vehicle.dbc, the wowdev link is heavily out dated from the looks of it, trying to figure out what the ID actually represents.

Thanks in advance.