The integration of text and graphics is probably the single most problematic issue in electronic publishing. Document processing systems take many different approaches to the problems involved.
Some systems import the graphics into the document.
Others point to external files. Others convert the graphics into an internal format. Invariably, each document processing system has its own level of understanding of the graphics formats it can use. The formats themselves impose restrictions on the ultimate flexibility possible. It is important to understand the types of graphic formats a particular document processing system can use.