Musical scores annotation is a well-known practice from musicians, especially in educational terms. It consists in adding written comments to a score in order to make a phrase explicit and thus facilitate the learning of the piece and its performance. However, this practice raises knowledge transmission issues: how to share and preserve the information within the annotation without altering it? Indeed, the author is often the only person who knows rhe meaning of his annotations. As the use of digital tools constitutes a privileged way to solve this issue, we first explore the existing solutions for sharing performances through annotations, as well as their pros and cons. Then, we propose an optimized solution to annotate scores online in order to maintain the intent of the author, i.e. make it explicit to other performers through our tools. This proposition focuses on four main aspects of score annotation: the annotation nature, its symbolic and semantic representation, its indexation on the studied piece and at last, the communication structure that supports it.