Rests are usually represented with
z; they can be assigned a length just like notes.
X:1 L: 1/4 C z D F | z2 C D
If you don’t want the rest to be printed on the score, use
X:1 L: 1/4 C x D F | x2 C D
Invisible rests can be useful for purposes of layout.
For multi-measure rests you can use the uppercase variants
X, followed by the number of measures they apply to.
X:1 L: 1/4 C D | Z4 | C D E F | X4 | C D
I guess it’s time for some rest, isn’t it?