In most cases the URL is automatically handled by APEX and the developer does not need to understand it. However with more advanced use of APEX comes the need to manually specify certain aspects of the URL. The following is a quick explanation of how the URL is constructed.
For this explanation we will focus on the f?p= part of the URL and explain each specific parameter
1 – The number or alias of the application you wish to run. The alias can be set in shared components -> definition
To access the current application id, use &APP_ID.
2 – The page number or page alias. The page alias can be set in the page attributes
3 – The session. to access the current session, use &SESSION.
4 – The request term that you want to pass to the destination page
5 – DEBUG. Decide whether the page is run in debug mode or not. either YES or NO
6 – This parameter can accept two values. RP = resets the pagination of the destination page followed by a comma separated list of pages where you wish to reset the cache. So for example if you want to reset pagination and reset the cache for pages 1 and 2 you would include “RP,1,2” for this parameter
7 – Comma separated list of page items to assign values to.
8 – Comma separated list of values to assign to the page items specified at position 7. The values must be in the same order as the page items are
9 – Printerfriendly. Determines if the page is being rendered in printer friendly mode. YES or blank