There are three types of triggers:
Form level
Block level 
Item level
If you want to validate the values of an Item, usually use 
Item level trigger, such as POST-CHANGE trigger.

In a Report of more than 1 page information. Then BETWEEN
PAGES trigger fire when one move from one page to other
page. In this trigger we can write process which is required
to affect other page values.

in Forms 10g now there is RUN_REPORT_OBJECT(report_id, 
parameter_list) is to use for run report 
Use this Built-in RUN_REPORT_OBJECT to run a report from 
within a form. You can run the report against either a 
local or remote database server.
Before 10g we were using Built-in procedure RUN_PRODUCT.

max of 12

max 12

Max 12 types we can use before/after combination

use sign() with decode()

select sum(column_name) into l_return from table_name
where column_name >=0

paste this in a formula column and make it the source of 
sum amount..

SELECT SUM(COL_NAME) FROM 
 ( SELECT COL_NAME FROM TABLE_NAME
          ORDER BY COL_NAME DESC)
  WHERE ROWNUM<=4;

place holder colum's are used to strore the value of the 
varibale.

U cannot hide the program in concurrent program window at 
the most u can diable it and u can hide the report in the 
SRS by "uncheck use in SRS chkbox"

Create a text item change its Item Type property to Radio 
Group. now the text item is changed to radio group expand 
the item u will see radio button click on that andgive add.

The Restrict List to Predetermined Values is a checkbox 
that indicates whether a value for the parameter must be in 
the list of values.  For example, if you check Restrict 
List to Predetermined Values and the Initial Value does not 
match a value in the list of values, an error will be 
generated when you accept the Parameter property sheet.  
Similarly, if you set a value for the parameter on the 
command line or in a command script and it does not match a 
value in the list of values, an error will be generated 
when the report is run.  If you check Restrict List to 
Predetermined Values, a list of values will appear in the 
runtime parameter form.  If you do not check it, a combo 
box will appear (i.e., you can enter values as well as 
select from the list).