What determines when a field is shown in the Device column as a Yes/No field? I have the same field in two versions of an .iok file; in one version its a yes/no field (which is what I want) and in the second version, it's a Category type with the values "1,", "0", or "no value".
Yes/No or 'Boolean' fields (columns) use 3-way filters: Yes/No/All on the Sidebar, and therefore can contain only 2 valid values. You cannot have blank/null values in a Boolean field, or it will revert to a normal 3-Category field.
In fact you can have either:
(1) a mix of Yes and blank values (nulls)
or
(2) a mix of Yes and No values
But you cannot have a mix of Yes, No and blanks.
Providing this conforms, the field will default to "Yes/No" and you will be able to change the filter type using the filter's configure menu.