The assembly syntax is supposed to be upward compatible with that described in Sections 1.3 and 1.4 of `The Art of Computer Programming, Volume 1'. Draft versions of those chapters as well as other MMIX information is located at http://www-cs-faculty.stanford.edu/~knuth/mmix-news.html. Most code examples from the mmixal package located there should work unmodified when assembled and linked as single files, with a few noteworthy exceptions (see MMIX-mmixal).
Before an instruction is emitted, the current location is aligned to the next four-byte boundary. If a label is defined at the beginning of the line, its value will be the aligned value.
In addition to the traditional hex-prefix `0x', a hexadecimal number can also be specified by the prefix character `#'.
After all operands to an MMIX instruction or directive have been specified, the rest of the line is ignored, treated as a comment.