Cargo Features

[dependencies]
tss2 = { version = "0.1.3", default-features = false, features = ["sys", "esys", "fapi"] }
default = esys, fapi, sys

These default features are set whenever tss2 is added without default-features = false somewhere in the dependency tree.

sys default
esys default
fapi default

tss2 has 4 features without comments.