All bytecodes have one explicit operand, at most. However, assembler instructions for some of them seem to allow for one extra argument (see below). Please note that this is only a notation device — a way to tell assembler to adjust target address after converting label number or base address into a final offset (stack-, object-, or buffer-relative).
Suppose the Cybiko C compiler sees something like this:
int my_array[ 3 ];
...
my_array[ 2 ] = 1;
Obviously, there is no need to load index, scale it (since array elements are word-sized), then load address of the array, then add it to scaled index, etc. Instead, our compiler will produce something like this:
.label 777 ; my_array
.skip 6
...
leag.u 777 4 ; my_array
move
load1
storeis
Here, 777 is label number (ordinal), 6 is the size of my_array[], and 4 is extra displacement relative to the label 777. Note that assembler will turn 'leag.u 777 4' into a single opcode followed by the word-sized displacement (hence .s suffix).
Note that instruction suffixes designate optional data that may follow (and not the size of the operands):
.c char (that is, signed byte),.b byte (unsigned byte),
.s short (16-bit signed word),
.u unsigned short (16-bit unsigned word),
.w word (16-bit unsigned word),
.l long word (32-bit signed double word).