This work presents an XML-based authoring methodology that facilitates the different tasks associated with the development of standards-compliant e-learning content development. The idea is to support a unified authoring process of adaptive e-learning content by adopting the manual writing metaphor. According to this metaphor, which is specially well-suited for technical domains, instructors are compelled to view e-learning material as the manuals normally written and used to teach a particular subject. The methodology is supported by the DocBook document model (an XML application) which has a number of tools associated that facilitate the implementation of the methodology. Other tasks such as the packaging of contents or publishing in the Learning Management System (LMS) can be automated from these manuals.