Tag (documentation 1.4.0 API)

```
@Target({METHOD,TYPE,ANNOTATION_TYPE})
@Retention(RUNTIME)
@Documented
@Repeatable(TagList.class)
@API(status=STABLE,
     since="1.0")
public @interface Tag
```
Use @Tag("a tag") to give test classes, groups and methods an (additional) tag which can later be used to select the set of tests to execute.
You can have many tags on the same element.
Tags on the JUnit platform must obey a few rules:
- A tag must not be blank.
- A trimmed tag must not contain whitespace.
- A trimmed tag must not contain ISO control characters.
- A trimmed tag must not contain any of the following reserved characters.
  - ,: comma
  - (: left parenthesis
  - ): right parenthesis
  - &: ampersand
  - |: vertical bar
  - !: exclamation point

- Required Element Summary
  
  Required Elements
  Modifier and Type Required Element Description
  
  java.lang.String value

- Element Detail
  - value
```
java.lang.String value
```