The model in MVVM

Unless I misunderstand - Most of the articles I read on MVVM explains model in MVVM as the piece holding domain/business-logic, but what baffles me is that MVVM is a presentation layer pattern and presentation layer does not hold business logic in entirety. Can some please help me understand how the domain-logic in business layer maps to the model in the presentation layer, is the model in MVVM actually a DTO? I'd appreciate if some one can help explain with an example how business layer is mapped to a MVVM model in SOA (business logic sits behind a web service). Thanks.