  This article aims at reengineering of PDF-based complex documents, where
specifications of the Object Management Group (OMG) are our initial targets.
Our motivation is that such specifications are dense and intricate to use, and
tend to have complicated structures. Our objective is therefore to create an
approach that allows us to reengineer PDF-based documents, and to illustrate
how to make more usable versions of electronic documents (such as
specifications, technical books, etc) so that end users to have a better
experience with them. The first step was to extract the logical structure of
the document in a meaningful XML format for subsequent processing. Our initial
assumption was that, many key concepts of a document are expressed in this
structure. In the next phase, we created a multilayer hypertext version of the
document to facilitate browsing and navigating. Although we initially focused
on OMG software specifications, we chose a general approach for different
phases of our work including format conversions, logical structure extraction,
text extraction, multilayer hypertext generation, and concept exploration. As a
consequence, we can process other complex documents to achieve our goals.
