Use a pop up menu format instead of drop down list. Then the 2nd field value (apparently the _display field) will be what shows when you move on to the next field or record.
Option 2: (This one's sneaky, I'll use the "attribute" tables in my example and leave it to you to generalize the method for use with the "content" tables)
Add the Attribute_display field to your layout. Use the Inspector's behavior settings to deny access to this field when in browse mode. Give it an opaque fill color and place it directly on top of your drop down list formatted field so that the drop down list field is fully hidden from view. If you want the drop down arrow to be visible and this is FIleMaker 12 with rounded fields, give the attribute_display field a drop down list format so that you can specify the drop down arrow so that it looks like a drop down list. If the field is rectangular as you find in FileMaker 11 or in Classic themed layouts in 12, you can just resize this field so that only the arrow from the drop down list field is visible.
When you click on this field, the drop down list field hidden behind it pops to the front and you can use the drop down list to select a value. When you select a value, the drop down list disappears back behind attribute_display and attribute_display then shows the more nicely formatted version of this information.
Awesome. I wonder why the pop up menu format works that way.... but it does.
OK - another related question. How can I allow for a "+" type button next to sit next to the pop up menu(s) to allow for a dynamic number of tags to be assigned to each observation_id? So if a user wanted 1 tag they would just use it once, but if they wanted 2, or 3, they could hit the + and a new field would pop up. Does this make sense?
Not really. I'd use a portal to the join table for recording observations and then you can add as many tags as you want by entering/selecting each one on as many rows of that portal as you need.
That worked great. However, I am trying to figure out how to allow a user to delete or remove a term once chosen from the drop-down list, and also how to restrict duplicate entries of the same term for individual records. For instance, I do not want observation 7 to be able to have the same attribute more than once. I'm going to guess there is a validation routine for this, but since I need the __attribute_slug_fk to only occur once for each __observation_id_fk on the ObservationAttributes table I am not sure how to specify this.
To delete a term, you use delete portal row to delete the join table record. If you set up a text field with an auto-enter calculation that combines the selected value with the correct foreign key, you can specify a unique values validation on that auto-enter calculation.
This demo file, may be useful to you: https://www.dropbox.com/s/oyir7cs0yxmbn6i/ManyToManywDemoWExtras.fp7