SLNX is a new XML-based file-format for .NET based solutions, replacing the older proprietary SLN file-format. Unlike SLN-files, it is merge-friendly and expected to become the new the de-facto standard for working with .NET projects. This commit adds support for SLNX-schema to nxml-mode. When opening SLNX-files in Emacs and activating nxml-mode, no special schema-validation or completion/assistance is provided. Attached is a patch which corrects this situation. (SLNX-files not added to any auto-mode-list, because I couldn't find where/if that is done in the nxml-mode codebase). — Kind Regards Jostein Kjønigsen