There is a difference between the fields that show up in the source manager and the important fields. The fields that show up are the same for all styles. The ones that are important, are style dependant.
When Microsoft defined the open xml specification, they allowed all fields for all types of sources. It is a 'flat' format. Basically, they allowed for adding a 'station' field to a 'book' (pointless). The people who created Word decided that that
was too much freedom for the end-user and picked a subset of fields which they support for each type. A good idea, but unfortunately their 'picking' was miserable. You would expect that in the 21st century, they would have added at least the 'electronic
fields' to each type of entry or provided extra types of sources for them.
Anyway, you can decide yourself which fields to attach to which source.
The lazy solution: switch between source types
In the source manager, when you change the type of a source, different fields will become available. You can switch to a type of sources which has the fields you want, and fill them in. Then, when you switch back to the type you want, the data will be kept
although it looks like the fields are gone.
The good solution: edit bibform.xml
The above works if you only have one or two entries. If you have dozens of entries, it becomes a stupid thing to do.
The order and availability of the elements for a given source type in the source manager is defined in a file called
bibform.xml. Normally, this file can be found in
C:\Program Files\Microsoft Office\Office12\1033\Bibliography
where the 1033 could be a different number for you. It represents the localization of your copy of Word (1033 = US English).
If you open the file you will notice a huge bunch of xml code. Its format is pretty simple and straightforward. For each type, there is an entry in the form:
<Source type="JournalArticle" display="Journal Article">
<!-- all definitions -->
The children of a source element are the different fields that will be available in the source manager for that type. For example:
<Sample>Example: Adventure Works Monthly</Sample>
What you can do is copy paste the electronic fields from other source types inside the Source element for JournalArticle. You would want to add the following code inside the Source element:
If you save the file and try to edit a Journal Article source, all fields should now be available. Note that you might want to select "Show all fields" depending on how you defined your important fields.
I added the "Medium" field as an extra to your requirements. It depends on where you want to display the word "online" in your format. If you do it near the URL, then you won't need a field for it. However, if you do it for example directly
after the title and in before the journal name, you might want to put the word "online" in the "Medium" field and display that field. BibWord is not capable (yet) of showing a string based on the fact if a field is available without actually
displaying the field.