An annotation that may occur multiple times at a single program element, and only on certain program elemenets.

A sequenced annotation is declared simply by having the annotation class satisfy SequencedAnnotation instead of Annotation. For example the following would only be allowed on class declarations, functions or methods:

alias ExecutableDeclaration 
       => ClassOrInterfaceDeclaration|FunctionDeclaration
"Documents a pattern that the annotated element is particpating in"
final annotation class Pattern(String name) 
        satisfies SequencedAnnotation<Pattern, ExecutableDeclaration> {
}

At runtime a ceylon.language.meta.declaration::Declaration instance can be queried for its SequencedAnnotations of a certain type using ceylon.language.meta::annotations or ceylon.language.meta::sequencedAnnotations.