FLAT is a web-based linguistic annotation environment based around the FoLiA format (http://proycon.github.io/folia), a rich XML-based format for linguistic annotation. FLAT allows users to view annotated FoLiA documents and enrich these documents with new annotations, a wide variety of linguistic annotation types is supported through the FoLiA paradigm. It is a document-centric tool that fully preserves and visualises document structure.
Features
Web-based, multi-user environment
Server-side document storage, divided into 'namespaces', by default each user has his own namespace. Active documents are held in memory server-side. Read and write permissions to access namespaces are fully configurable.
Concurrency (multiple users may edit the same document similtaneously)
Full versioning control for documents (using git), allowing limitless undo operations. (in foliadocserve)
Full annotator information, with timestamps, is stored in the FoLiA XML and can be displayed by the interface. The git log also contains verbose information on annotations.
Annotators can indicate their confidence for each annotation
Highly configurable interface; interface options may be disabled on a per-configuration basis. Multiple configurations can be deployed on a single installation
Displays and retains document structure (divisions, paragraphs, sentence, lists, etc)
Support for corrections, of text or linguistic annotations, and alternative annotations. Corrections are never mere substitutes, originals are always preserved!
Spelling corrections for runons, splits, insertions and deletions are supported.
Supports FoLiA Set Definitions to display label sets. Sets are not predefined in FoLiA and anybody can create their own.
Supports Token Annotation and Span Annotation
Supports complex span annotations such as dependency relations, syntactic units (constituents), predicates and semantic roles, sentiments, stratements/attribution, observations
Simple metadata editor for editing/adding arbitrary metadata to a document. Selected metadata fields can be shown in the document index as well.
User permission model featuring groups, group namespaces, and assignable permissions
File/document management functions (copying, moving, deleting)
Allows converter extensions to convert from other formats to FoLiA on upload
In-document search (CQL or FQL), advanced searches can be predefined by administrators
Morphosyntactic tree visualisation (constituency parses and morphemes)
Higher-order annotation: associate features, comments, descriptions with any linguistic annotation