  This demonstration paper presents StreamSide, an open-source toolkit for
annotating multiple kinds of meaning representations. StreamSide supports
frame-based annotation schemes e.g., Abstract Meaning Representation (AMR) and
frameless annotation schemes e.g., Widely Interpretable Semantic Representation
(WISeR). Moreover, it supports both sentence-level and document-level
annotation by allowing annotators to create multi-rooted graphs for input text.
It can open and automatically convert between several types of input formats
including plain text, Penman notation, and its own JSON format enabling richer
annotation. It features reference frames for AMR predicate argument structures,
and also concept-to-text alignment. StreamSide is released under the Apache 2.0
license, and is completely open-source so that it can be customized to annotate
enriched meaning representations in different languages (e.g., Uniform Meaning
Representations). All StreamSide resources are publicly distributed through our
open source project at: https://github.com/emorynlp/StreamSide.
