How do you get a handle to the document currently in the workflow?

According to SharePoint Monthly Expense Claim Tutorial, Step 9: Update Document Properties, you should be able to browse through this hierarchy:

XMLFields
--the process name ("Expense Claim" in the tutorial)
  --WFIProcessField
    --Name

But, in my Context Browser, I see this

XML Fields
  --the process name ("Marketing Approval" in my case)
    --WFIProcessField
      --Items
        --Type
         --Item
           --ID
           --SiteURL
           --ListURL
           --FolderURL
           --Item
           --URL
           --Source
             --SiteURL
             --Library
             --Folder
             --Name
             --URL

I figured the most likely candidate was the "Name" attribute (2nd from last above).  When I drag this to the File Name field, it calls it WFIProcessField_Name, which makese sense.  But when I run the workflow, it generates an error:  "An error occurred while parsing EntityName.  Line 1, position 294."

 Any ideas which attribute I should be using?