Ink is stored in a data structure that permits later retrieval by applications. The ink includes stroke information and property information. Properties may be associated globally with the ink strokes and/or with each stroke individually. Aspects include a data structure that supports ink for multiple applications. Using the storage system, method, and data structure, various applications may expand on ink to include additional attributes while permitting the ink to be used in applications not supporting the additional attributes. When encountering an unknown tag, the applications will skip past the end of the tag and its associated data to start reading the next tag.