Adding New Value for Field In Attribute Table prevented?

Question

I have a polyline feature class in ArcGIS (version 10.3.1). There are only four options for the field "Type" (five if you include Null):

The symbology for this feature class was imported from a template feature class. I now want to add a new value for "Type" - "Footpath Redirected". I've added this to the "Unique Values" in the "Symbology" of the "Properties" of the feature class:

However, when I try to change a feature's type in the attribute table, I still have only the original four options (five if you include Null), as per the first screenshot.

What is the error in my approach?

Answer 1

I'm guessing there's either a domain or subtype on that field. If so, you'd need to add the value you want in the gdb there.

If this is a shapefile, don't know.