Type of Shimano "PlusMinus" (slot & Philips) screws Shimano uses a screw type that is a mixture between slot and Philips (PH):



There's a "PlusMinus" screw type for electrician equipment like manufactured by Wiha :



(Source: Wiha)

Are the Shimano screws officially PlusMinus types? Are they officially Philips (PH) compatible?
As far as I know, every cross-type Shimano screw is JIS, or at least they are in the sense of being designed to mate correctly with a JIS screwdriver. The limit screws you mentioned just are extended a bit to handle a flat screwdriver if that's what's handy.