Staying more than 90 days usually results in being granted a National Visa for students and visitors on business. There are specific requirements for these over and above those accompanying a Short-stay Visa application. If you are planning to study in a Schengen country, then a letter from the educational institution will be required. If you are working, then documentation from your place of business explaining the reason and length of time you will be expecting to stay in the Schengen zone is necessary.