Idicator Strips (New SDK)
I'd suggest looking in the VMF, but you said you already did that. I haven't looked at that map myself so I'm not sure what all is in there.
msleeper wrote:
Click on one of the indicator strips on the floor and check it's name. Then, click on the Output tab to see what is sending commands to it, and click Mark. That will highlight the entity that sent the commands, but you'll have to move around the camera to find it exactly. Look at the Inputs to see exactly what it is doing.
Alright, I think that answers a big chunk of how they're connected, but I'm still not seeing how these info_overlay_accessors are in any way, connected to the info_overlay they are toggling. 
EDIT Korjagun beat me to the chase.
Korjagun wrote:
Actually the indicator strips seem to be toggled by an env_texturetoggle just like we used to do it before. It's hanging around in the left corner of the room in the sample map; note that its target is "doorstate_a02b_left", which matches the indicator strip overlays.
Nothing in the indicator strip overlays themselves, say anything about "doorstate_a02b_left" or what ever is being targeted. That's what is confusing me. The indicator strips seem to have no link to the texture toggle or the overlay assessors at all!

PS: I am still working on this while waiting for reply s, I haven't just given up and am sitting here waiting mindlessly for the answer. I am still trying.

EDIT: Judging by your screenshot, you have multiple (differing) entities selected. Switch to object select mode and just select the strip and not whatever else it happens to be grouped with.
Here's a screenshot of a single overlay selected.

Edit: I should also mention that this is actually map: testchmb_a_00_d
EDIT:
Quote:
Edit: I should also mention that this is actually map: testchmb_a_00_d
Is that decompiled? Then perhaps something was lost in the decompilation process, especially if it was assuming pre-orangebox BSP files. Have a look at the map provided by Valve as part of the SDK update.
Edit:
Thank you so much! "Your assistance is appreciated."
That worked, and now I know I have a map source to learn from, as opposed to decompiling the official maps. The indicator strips work beautifully! 
msleeper wrote:
In fact, someone should do a tutorial on the Wiki!