It's exactly as it appears. Wide for wider light cast. I couldn't find it in the manual either though it shows up in the brochure & this schematic:

You'd just have to take out & rotate the bulb within the ring frame to keep the pilot screw in position. In our 15x30 IG, the light casts well on Standard, but if you're installing it on a side wall or wider pool, you might want to give the Wide setting a shot.
PS- The manual also seems to lack an order of the color programs. Seems like something they'd include, no? Haven't tracked that down yet :-)

Enjoy.