Assign a Transaction to Report

I want to assign a transaction to a report.

In the initialization event of the report,

a function is invoked. The result returned

from the function is used to determine

the initial screen to display.

When assigning a transaction to the report,

I am prompted to identify the initial screen

to display, but as mentioned above this is

not known until runtime.

How can I configure the transaction to accomodate

this situation?