Meta-annotations (metaprogramming with annotations)
AST transformations can be specified on annotations. Doing so allows to perform specific transformations when annotating a given class, field, method and/or field.
Marcel's standard library provides many annotations useful to avoid writing boilerplate code. Some of them are similar as the one you could find in Lombok.
Meta-annotations from the Marcel's standard-library are all lowercase (even the first letter), this is how you can differentiate them from other (non-meta) annotations.