Although MPEG-21 has the power to become the underlying protocol for content creation and content exchange applications, obstacles can be identified, which might impede its potential powerful position. These obstacles would result from an incomplete set of requirements if not all relevant use cases are considered thoroughly. Additionally, potential users might not be aware of the possibilities provided by MPEG-21. Within the MUSICNETWORK [MN] project, interests of people distributing music and musical related content are represented. One of the activities of MUSICNETWORK is the contribution to standardization activities. Several application scenarios are currently being investigated in order to overcome both previously mentioned obstacles. We sketch the "sheet music publisher" application scenario and describe one use case in detail. Based on these use cases we derive requirements and explain how MPEG-21 can influence this use case.