What does the EF-S indicator on my C100 Mark II viewfinder indicate?

[Bent-kenda]

I just got a C100 mark ii a month ago and I have had the same lens on for a couple weeks but just now noticed the EF-S yellow indicator on my viewfinder/LED screen. What does it mean? I wasn't sure if I accidentally enabled something. 

[Anonymous]

Do you have an EF-S lens attached to the camera? See this from the manual:

 Here is your camera's manual download:
https://gdlp01.c-wss.com/gds/8/0300017408/08/eosc100-mk2-im8-en.pdf 

[IamintheUK]

Some EF-S lenses can have some light fall off at the edges so this setting crops in on the sensor to eliminate it. With the Canon EF-S 18-135mm IS STM lens on my C100 mk2, I haven't noticed any darkening of the edges of the frame so I keep the EF-S setting off.

[rs-eos]

The sensor size on the C100 Mark II is 24.6 x 13.8 mm.  An APS-C sensor should be 25.1 x 16.7mm.  So the C100's sensor is a tad smaller.  Thus, any vingnetting wouldn't be any worse (should actually be a tiny amount better) than if using that same lens on an APS-C photo camera.   So would also leave that setting off.

If instead, the C100's sensor was wider like the EOS C70 (26.2mm), then I could then see the need to have that feature enabled.