Is it possible to create an SVN repo with the two directories, "htdocs", and "global", and add it at the root of a repository that already has a folder called "htdocs".
My aim is to have the files from the external repository to mix in with the project directories, for example, putting in common CSS files, etc.
Thanks up front.
No, unfortunately you cannot "mix" the contents of two directories, or overlay a directory with the contents of an external reference.
For an svn:externals you need always to specify a foldername and an URL(of a working copy) the folder will be created below the folder with the externals-property and will checkout the URL.