When an application presents a user with a list of items, it's pretty common that it permits the user to filter the items. Often a 'filter' feature is implemented as a set of include or exclude rules. For example:

• include all emails from [email protected], and
• exclude those emails without attachments

I've seen this include/exclude pattern often; for example Maven and Google Analytics filter things this way.

But now that I'm implementing something like this myself, I don't know what to call something that could be either included or excluded. In specific terms:

1. If I have a database table of filter rules, each of which either includes or excludes matching items, what is an appropriate name of the field that stores include or exclude?
2. When displaying a list of filters to a user, what is a good way to label the include or exclude value?

(as a bonus, can anyone recommend a good implementation of this kind of filtering for inspiration?)