Oh, DSL is a bit of Developer jargon, meaning 'domain specific language', which is to say some sort of 'computer language' that is meant to solve one specific type of problem. So, what I developed deals with authoring structured data in ways that allow it to be processed as required, say to make an HTML document out of it, or a database, etc. all from the same text.
DTP is just an acronym for Desktop Publishing. DTP programs are things like Page Maker or whatnot that are a bit like Word Processors, except intended to produce very precisely formatted and organized printed material (actually these days they output PDFs of a specific type that is optimized for cutting plates for offset printing and such).
So, in things like publishing (as well as software development) workflow is really the big issue. You need to be able to assemble data (text, images, business logic, whatever) and construct your final product (a book, a program, etc.) However it also has to be reproducible and possible to easily make corrections, maintain version control, automatically create related artifacts like indices, SRDs, etc. Those workflows also are going to have to allow for many people to work at the same time on the same project etc. Structuring the work on projects like this is actually MORE difficult, or can be, than doing the work itself. It definitely requires a lot of expertise and care.