This summary is not the rule. The rule text controls.
If you get a subpoena to appear in court as a witness, you have to show up at the time and place listed, and you have to stay until the court says you can leave. If you skip out early or don't show up at all, the court can have you arrested and brought in. This is called being "attached."
This rule gives courts a way to make sure witnesses actually follow through on their legal duty to testify. Ignoring a subpoena isn't something you can just brush off. If you're worried about attending or need to leave early for some reason, the right move is to talk to the court or an attorney beforehand instead of just not showing up or walking out.
