The SSMN Spatial Taxonomy and its symbols libraries, which are the corner stone of the Spatialization Symbolic Music Notation (SSMN) project, emanates from research into composers' attitudes in this domain. It was conceived as the basis for the development of dedicated notation and rendering tools within the SSMN project. The taxonomy is a systematic representation of all relevant features necessary to specify sound spatiality: shape and acoustic quality of the space, structure, position and movement of sound sources. It is based on single descriptors that can be combined in order to define complex spatial configurations. Descriptors can be transformed locally and globally and can be the object of structural and behavioral operations. The SSMN Spatial Taxonomy proposes a corresponding graphic symbolic representation of descriptors, operations and other functional elements facilitating the communication of creative ideas to performers and technical assistants. This paper focuses on the presentation of the taxonomy and the symbols. Additionally it describes the workflow proposed for using symbols inside a notation software prototype developed within the project. Finally, further aspects concerning the actual and future developments of SSMN are mentioned.