home-files-service-type - naming restrictions?

[Paul Jewell]

Good afternoon,

I have a home configuration which has worked without issue for some 
time, but now I wanted to add the configuration files for urxvt:

(home-environment
  (packages ...)
  (services
    (list
      ...
      (simple-service 'urxvt-config
        home-files-service-type
          (list `(".Xresources"
                  ,(local-file
                    "/home/paul/dotfiles/home/file/.Xresources")) 

                `(".config/urxvt"
                  ,(local-file
                    "/home/paul/dotfiles/home/files/.config/urxvt")))))

I am getting the error:

guix home: error: invalid name: `.Xresources'

This leads me to three questions:
1. Is there a constraint on file naming with home-files-service-type?
2. If so, is there another mechanism I am supposed to use to create 
.Xresources?
3. So I can find my way through this type of problem in the future, is 
there some way I can see the source code to home-files-service-type 
apart from digging? For a package, I know I can use guix edit <pkg-name> 
to see the definition, but I can't see how to do this for 
home-files-service-type.

Thanks!