Minecraft wiki entry for Target_selectors, associated text: [x=<value>,y=<value>,z=<value>] — Define a position in the world the selector starts at, for use with the distance argument, the volume arguments, or the limit argument. Using these arguments alone will not restrict the entities found, and will only affect the sorting of targets. Cannot duplicate any one of these three arguments.
The positional components are doubles, allowing for values like +12.34, and they are not center-corrected, meaning x=0 is not corrected to x=0.5.
In Bedrock Edition, tilde notation is available for selector argument coordinates.
In Java Edition, these arguments limit the search of entities to the current dimension.