Solidity v0.4.24 (solc-js)
I believe the fixed and ufixed are upcoming types. fixed and unsigned fixed are most certainly float with a defined decimal part. uint256x75 with a 75 bits decimal part. I would believe that it means that the integer part become 181 bits.
The following code
int256 constant public data = 200 / 3;
generates the error below at compile time:
TypeError: Type rational_const 200 / 3 is not implicitly convertible to expected type uint256. Try converting to type ufixed256x75 or use an explicit conversion.
Other error encountered:
UnimplementedFeatureError: Not yet implemented - FixedPointType.
More about this: https://github.com/ethereum/solidity/issues/3200