NULL format display when upgrading to 10.1.2

It seems that when you upgrade from a previous version of Discoverer to 10.1.2 that the existing default setting for null values has changed from blank to the word NULL. This is annoying because it means that the default display for null values in 10.1.2 is not the same as it was in previous releases. What this means is that old workbooks that contain null values will now display the word NULL instead of blank. One of my customers reported this to Oracle as a service request and received the following reply:

You will need to open each and every workbook, make the change and resave. There is no global setting to apply for previously created and saved workbooks unfortunately.Hope the above information was informative. If this answers your question kindly close the TAR else feel free to update the TAR.

My customer has 100s of workbooks and it will take some time to go through this. I pity the person who has 1000s of workbooks because they will have to do this for each and every one! Don't be fooled into thinking that what you set in pref.txt will help because it won't. The upgrade is done using Discoverer Administrator which does not even know of the existence of pref.txt so it will ignore whatever you have set and will use its own default which is NULL.

If anyone knows of a workaround please let me know. Otherwise, if you have encountered this issue yourself please share your experience.