(;) ending expression and row separator
Semicolons are used to separate rows in a matrix definition (within brackets).
Semicolons may also be used at the end of an instruction (in a file or in Scilab console). In this case it means that the result(s) is(are) not displayed. Conversely use comma (,) to get the display.
a=[1,2,3;4,5,6];
a=1;b=1,c=2