Along with the main attributes; ID, Name, Group, Key, Description, Comment there are categories assignable to each item type.
Different categories can be assigned to each item type, these are used to query and sort your database items. Categories can be free form text, pick-lists of values you defined in the project schema or abstract data type including date, time, real, and integers.
Categories can also hold multiple values at the same time, for example a category called composition may contain a pick list of steel, glass, aluminium, brass. The item's category can be set to hold one or more of these elements depending upon what it will be manufactured from.