A GEDCOM relies on a data base, and in most applications it works with a "lineage linked" form. This is the form most commercial developers of genealogical programs use. It is possible to use the GEDCOM data format level to work with other forms of stored data, I believe, but I have no experience in that area.
So to answer your question, Hans-Georg, no, it would not be possible to convert "word-files" into a GEDCOM. You would need some sort of database to be able to do that.
If you wish to delve into the intricacies of GEDCOM Standards, have a read of the standard which can be found on: http://www.gendex.com/gedcom55/55gctoc.htmhttp://www.gendex.com/gedcom55/55gctoc.htm It is quite a technical document but does give a good insight into just what makes up the GEDCOM standard.