What Unspecified and Unspec means?
Those are defaults terms shipped with the application. It is usually shown as -UNSPECIFIED- or as -UNSPEC-.
The system will require information recorded in some category fields used with a centre, company, department, employee category, office or partner. However, there may be circumstances where you do no want to assign a category to a specific area or responsibility. In these cases, you can select -UNSPECIFIED- or -UNSPEC-.
However, care must be taken because over-use of the default will impact system reports and resourcing features.