forum topic http://forum.joomla.org/index.php/topic,84676.0.html
The end result is that there is a confusion over how these links work in practice. A fundamental point needs to be made in the help page.
I also feel that this should be added to a note / tooltip in the admin so I have submitted it as an enhancement on the tracker.
Here is a copy of that:
Suggestion for help page addition:When you add a link of type url to a menu for an internal page, most people will copy the link from the browser. This will mean that the Itemid is included in the link.
In this situation, joomla (rightly) does not generate a new Itemid for the new linked page. Most people are unaware of this and if they want to have specific module / template assignments on that page, they can't as the page will not show up in page assignment lists.
People need to be aware that if they want to do specific module / template assignments for their new link - url, then they must remove the Itemid=xx from the url that they add in the new link.
If we use this url for a sub album in a pony gallery component, it will NOT have the ability to assign modules to it specifically
But if we reve the Itemid, like below, it will allow module assignments
Joomla seems to be working perfectly, to provide both options, it is just that most users will not be aware of this.
I will submit a suggestion to the Documentation forum for the help page, but I think that people would just not realise that there were 2 ways of doing it. I do not think that they would naturally look at the help page.
I suggest that this should be included as a note or tool tip on the add link - url admin page.
Important note regarding module / template assignments for links of type URL:
When linking to internal joomla pages, there are two possible outcomes for module assignments depending on the url that you supply for the link.
If your link includes an existing Itemid e.g. &Itemid=65
Then joomla will generate a menu item with the same Itemid, and module assignments for your new menu link will be the same as those of the original page you copied the link from.
e.g. if you link to a sub page of a gallery component, and it includes the Itemid from the gallery component link, then module assignments will be those of the main gallery component link.
If your link does not include an Itemid ( you may remove it if you wish ), then joomla will generate a new Itemid for your menu item and you will be able to assign modules / templates to that page specifically.