Rather than defining a parameter with a particular value, you can use Salesforce formulas to provide a limited amount of dynamic flexibility to your Conga Composer URLs. Say you’d like users of a particular profile to always generate PDFs from Conga Composer, whereas users of other profiles may choose whether to use the native file format or PDFs. You could accomplish this by using a formula to control the behavior of the FP0 parameter.

In this example, after the base URL, we’ve enabled the Default PDF parameter and made the Force PDF parameter (fp0) dynamic, based on the user’s Profile. For System Administrators, fp0 is disabled. For others, fp0 is enabled.

https://composer.congamerge.com
?sessionId={!API.Session_ID}
&serverUrl={!API.Partner_Server_URL_290}
&id={!Contact.Id}
&DefaultPDF=1
&FP0={!IF( $Profile.Name = "System Administrator", "0", "1")}

In practice, we would recommend using an ID, such as $Profile.Id, rather than a text string, such as the Profile Name. You can learn more about the Salesforce formula language by searching for Operators and Functions in the Salesforce.com online help.