whether to create separate master olink database files for for HTML and FO output

In this section of Bob Stayton’s book, it says that
you need to create separate master olink database files for HTML and FO output:

http://www.sagehill.net/docbookxsl/OlinkPrintOutput.html#PdfLinkingSetup

 

Is it absolutely necessary to set up separate olink database
files for HTML and FO output? Has anyone been able to avoid using separate
olink database files by specifying the olink.base.uri when you generate the target.db
file?

 

Regards,

Jeff Powanda