Re integers, it’s not the esoteric stuff, it’s the flexible, supposedly universal stuff: there’s like half a dozen varieties of varints across MessagePack, CBOR, Protobufs, ASN.1 *ER, etc.; even UTF-8 is just a (limited-range) varint encoding from a certain point of view. “Zigzag encoding” (using the least significant bit as the sign bit) is particularly insidious. And note that the (integer) exponent in IEEE floating-point formats is signed but not two’s complement: it’s in a biased representation instead.