The Oracle Application Express URL contains a number of parameters. These parameters are documented but the summary below is quick guide to get you started.
A typical URL takes the form :
http://www.examplesite.com/pls/apex/f?p=1:2:3:4:5:6:7:8:9
1 - Application ID or alias
2 - Page ID or Alias
3 - Session &SESSION. :APP_SESSION
4 - Request (eg PRINT_REPORT=REPORT_1) &REQUEST. :REQUEST
5 - Debug (YES or NO) &DEBUG. :DEBUG
6 - Cache setting
APP - Clear cache for whole application
SESSION - Clear cache for current user session
RP - Reset pagination
x - Clear cache for page x
y - Clear cache for item y
7 - Comma separated list of page items
8 - Comma separated list of values
9 - Printer friendly mode (either YES or blank)