FoLiA: Format for Linguistic Annotation - FoLiA is a rich XML-based annotation format for the representation of language resources (including corpora) with linguistic annotations. A wide variety of linguistic annotations are supported, making FoLiA a useful format for NLP tasks and data interchange. Note that the actual Python library for processing FoLiA is implemented as part of PyNLPl, this contains higher-level tools that use the library as well as the full documentation, validation schemas, and set definitions
At least the RelaxNG schema doesn't have it yet, very likely the validators stumble on it too? It is however documented since v0.11.
Arose from https://github.com/LanguageMachines/PICCL/issues/4