The analysis, especially the anchoring, of free?form ink annotations on mixed?content digital documents is more difficult than that of documents containing only text. In this paper, first, we present our work on analyzing the common user scenarios of ink annotations and their anchoring in such an environment, and we also present a unified way to define and analyze the anchoring of different types of an- notations. Then we describe how our ink parsing system integrates the anchoring of and annotation with the recog- nition of its type. The method can be used in a real?time heterogeneous document analysis system.