I agree that the IF condition can only test whether a field is empty or not. I tried to pull the content from the OrangeCD tag into a variable but was not successful. My plan was to then use a script to evaluate the content.

You could edit the theme to make the file name something other than "Notes.PDF," but the restriction is that it has to be the same file name for all albums so that the link that the template displays on the album page works. Remember that if having the direct link is not important to you, you can put any PDF file (and multiple ones at that) into the album's media folder and open a file from the list after clicking on "View Files."

The folder where OrangeCD is installed includes the "daxedit.exe" program, which can be used to edit themes. (You can also open the theme with any text editor to edit it, such as Notepad.) After starting daxedit, the right panel shows all of the tags (i.e., database fields) that are available, which is helpful to figure out how to refer to these tags in code.