Based on the description of the category links we will take now a look to the behavior of the menu ID for entries.

This is how the front-end menu looks after the assignment of the categories:

The entries will get the menu ID (Itemid) of the category where they are assigned to. If an entry is assigned to more than one category, the used menu ID in category view is depended on the category which the visitor has selected.

Example 1

In this first example we have an entry Radek, which is assigned to the categories Category A and Category B which is a sub category of the linked category Second Category.

If the user visits Category A the entry Radek will have the menu ID 53.

If the user visits Category B the entry Radek will have the menu ID 54 (the menu ID of the menu link Second. Also the pathway will change to the linked category.

Example 2

If an entry is assigned to a category and to a linked sub category within the same category path, the menu ID changes as soon as the visitor passes the first category where the entry is assigned. Normally such an assignment does not make sense, but it shows how the menu ID works.

We have an entry Sigrid which is assigned to First Category and to its sub sub sub category Category AAA. Sub sub category Category AA is linked to the menu as Important Category.
For the following examples we set Show Entries of Subcategories to yes.

We are in First Category. The entry Sigrid has menu ID 53 as the component menu link.

Now we passes First Category. The entry Sigrid has now menu ID 64 because now the category assignment of Category AAA will be shown. Category AAA is a sub category of Category AA which is linked in the Joomla! menu.

Now we are in Category AA which is linked in the Joomla! menu. The pathway changes according to that menu link.

If an entry is assigned to more than one category, sometimes there will be more than one menu ID valid. This happens for example on SOBI front-page or within modules (like the Latest Entries module). In these cases the first logical occurrence of an entry in a category is used.

In our example, the entry Radek has two valid menu IDs for the front-page. ID 53 and ID 54. ID 53 will be used here.