complete overview of joomla urls

[ewel]

I have been playing with Joomla for some time now and I am well on my way of making my first module. In the course of doing so I have had to gain some understanding of the Joomla urls and I did find enough around to get that basic understanding for example http://www.alledia.com/blog/joomla-urls/joomla-url-week-part-1-%11-default-joomla-urls/.

However I now feel I need to understand it completely, and I have not yet found anything that is complete in explaining the Joomla urls. Would anyone be able to point me to a resource that I have missed or provide explanations?

Let me start by summarising what I do know or think I know...

1. Every Joomla url starts with index.php or index2.php, including 3rd pp components.

2. I would have said that every joomla url then indicates a component but I see in the url of this forum that this is not the case - and I have no idea how to explain that url. When a component is active the rul shows option=com_nameofactivecomponent, eg option=com_content.

3. Joomla urls can show tasks, and these include view and edit as well as section, blogsection, category and blogcategory. I do not know what the complete list of tasks is and this is one of the questions I have. When there is an active task the url will show task=nameofactivetask, eg task=view.
However if I am not mistaken there is also something like view=whatever, but I do not know how and why.

4. Most of time time, in any case in the content component, the url will show an id in the form id=n, eg id=15. In the case of the content component I think the id is the id of the section, category or content item dependent on what is being shown, but I am not sure about that. If the page shows a section or category there would be a task or view of a section/category or blogsection/category and absent that what is being shown is a content item, or so it seems.

5. The itemid is added to the url to determine what modules are shown on a page and does not actually have a direct relationship with any page but to menu items (it might as well have been called menuitemid) and remains active until another menu item is clicked. the itemid shows in the url as itemid=n eg itemid=2.

6. To confuse matters it is possible that the url does not show the section-category-content item sequence but only one or two of these. How and why is a mystery to me.

Please correct me where I am wrong and add what I have missed. I hope that this thread will collect enough information to make it possible to write a concise but complete guide to Joomla urls, at least those of everything that comes with the standard installation.

I have not used Joomla 1.5 but understand it uses a different system so my post here is really limited to version 1x, which is apparently still the most used version - and I am sure that I am not the only one struggling to understand these urls.