In the Joomla Administrator back-end, under the menu item Help -> Joomla help you will see a general help area which lists all the available help screens on the left, with the content of the currently selected screen on the right. This list all the installed local help screens, except those installed within extension directories. It is important to note that the content list is always generated by scanning the contents of the local help directory regardless of whether local or remote help is being used.
Since the name of each file in the /administrator/help/ln-LN directory must be a valid key reference, Joomla uses this fact to automatically construct a language tag "JHELP_CONTENT_ARTICLE_MANAGER" by removing the extension, upper-casing and adding a "JHELP_" prefix.
The language tag is then looked up in the currently loaded language files and in this case en-GB.ini contains the entry
which gives the "key reference" as "Content_Article_Manager". This is then used to construct the URL which is used to retrieve the help screen. For example, if the help URL is
then this will result in the URL
in Joomla 1.6.x onwards. If the help URL is not specified then the default help URL is given by
resulting in the file