Not a bug
BYOND Version:512.1438
Operating System:Windows 10 Home
Web Browser:Chrome 67.0.3396.99
Applies to:DM Language
Status: Not a bug

This is not a bug. It may be an incorrect use of syntax or a limitation in the software. For further discussion on the matter, please consult the BYOND forums.
Descriptive Problem Summary:
Attempting to access/modify vis_contents through just atom instead of any of its derivatives throws an undefined var error. I don't believe this is intended since according to the documentation it should be under atom. It works fine for turfs, objs, mobs, & movable atoms.
Numbered Steps to Reproduce Problem:

Code Snippet (if applicable) to Reproduce Problem:
var/image/i = image('blank.dmi')
vis_contents += i

Expected Results:
Compiles code.
Actual Results:
error: vis_contents: undefined var

Does the problem occur:
Every time? Or how often? Every time.
In other games?
In other user accounts?
On other computers? Was tested on another computer running on beta.

When does the problem NOT occur?

Did the problem NOT occur in any earlier versions? If so, what was the last version that worked? (Visit to download old versions for testing.)


Does it work if you access it via vars?
vars["vis_contents"] += i
Lummox JR resolved issue (Not a bug)
vis_contents is not an atom var; it's a var under /turf, /atom/movable, and /image. Although the reference puts it under /atom/var for simplicity, it does specify that areas do not have the var.