Can't add ubytes together to make a ubyte... bug or feature?

[Dominikus Dittes Scherkl]

On Saturday, 17 March 2018 at 18:36:35 UTC, Jonathan wrote:
> On Tuesday, 19 January 2016 at 23:36:14 UTC, Adam D. Ruppe 
> wrote:
>> On Tuesday, 19 January 2016 at 22:12:06 UTC, Soviet Friend 
>> wrote:
>>> I don't care if my computer needs to do math on a 4 byte 
>>> basis, I'm not writing assembly.
>>
>> x86 actually doesn't need to do math that way, if you were 
>> writing assembly, it would just work. This is just an annoying 
>> rule brought over by C.
>>
>>> Can I prevent the initial implicit casts?
>>
>> Nope, though you can help tell the compiler that you want it 
>> to fit there by doing stuff like
>>
>> ubyte a = 200;
>> ubyte b = 100;
>> ubyte c = (a+b)&0xff;
>>
>> or something like that, so the expression is specifically 
>> proven to fit in the byte with compile time facts.
>
>
> `(a+b)&0xff` What is this syntax?!  Could you give a link to 
> this in the D documentation?  I am not even sure how to look it 
> up...
& is the normal binary and operation, same in C, C++, Java, ...
0xFF is a hexadecimal constant (255), which the compiler knows 
fit in an ubyte
So what do you not understand about this syntax?