What does the E suffix stand for?

[mattdiamond]

I noticed that OptionT, EitherT, and TheseT (along with their Task counterparts) have both match and matchE functions, but the Code Conventions FAQ doesn't cover the E suffix.

I can see that the E version uses chaining instead of mapping, so I understand the technical difference between these functions, but I'm just curious what word beginning with E is referenced here.

[gcanti]

IIRC "Effect"

[grossbart]

I added a brief explanation of the E suffix to https://gcanti.github.io/fp-ts/guides/code-conventions.html#what-an-e-suffix-means-eg-matche