${?}_{{?}_{{?}_{?}}{?}_{{?}_{?}}{?}_{{?}_{?}}{?}_r\text{e}\text{p}\text{e}\text{t}\text{i}\text{t}\text{i}\text{o}\text{n}is\text{s}\text{o}\text{m}\text{e}\text{t}\text{i}\text{m}\text{e}\text{s}\text{c}\text{a}\text{l}\text{l}\text{e}\text{d}\text{d}\text{e}\text{f}\text{i}\text{n}\text{i}\text{t}\text{e}\text{r}\text{e}\text{p}\text{e}\text{t}\text{i}\text{t}\text{i}\text{o}\text{n}\text{.}}$

counter$-$controlled

$sentinel-$controlled

variable$-$controlled

none $of$ these