These options " system/user" in filter refer to data retrival permissions for field which are governed by user permissions.
Following is the detail description of these options:
The Get Data As filter property allows you to specify the permissions that a filter
uses for certain operations. Prior to the introduction of this property, all filters in
AR System always executed with the permissions of an administrator. In other
words, by default, filters can read and write any field in any request, regardless of
the permissions on the field or on the request.
When set to User, the Get Data As property supports applications that use rowlevel
security and dynamic groups for access control. This property enables a filter
to adopt the permissions of the user that caused the filter to be called when
retrieving the data upon which the filter acts. A filter with this property configured
for user permissions can still write to any field on any request appropriate to the
operation, but can only retrieve entries and fields that are visible to the user that
caused the filter to be executed.
The Get Data As filter property has these values:
—Run the filter with the permissions of the Administrator. This is the
—Run the filter with the permissions of the user that called the filter.