AGTK (Annotation Graph Toolkit)
https://tla.mpi.nl/tools2/tooltype/annotation/agtk-annotation-graph-toolkit/

A suite of software components for building tools for annotating linguistic signals, time-series data which documents any kind of linguistic behavior (e.g. audio, video). The internal data structures are based on annotation graphs. Annotation Graphs are a formal framework for representing linguistic annotations of time series data. Annotation graphs abstract away from file formats, coding schemes and user interfaces, providing a logical layer for annotation systems. TLA-Team: The idea of the Annotation Graph Toolkit is based on the famous paper “Annotation Graphs” from Bird & Liberman which was the basis for tools such as ELAN. The AGTK does not seem to be actively maintained anymore. This will be added to Searching the Internet 2018 – The Primer. This will be added to Journalism Resources Subject Tracer™. This will be added to Knowledge Discovery Subject Tracer™. This will be added to Business Intelligence Resources Subject Tracer™. This will be added to Entrepreneurial Resources Subject Tracer™. This will be added to the tools section of Research Resources