Intersection table representing the resolution of a many to many relationship.

position_in_wb_s (FSK, M: CHAR VARYING(19))
position_in_wb_t (M: CHAR VARYING(16))
wellbore_act_s (FSK, M: CHAR VARYING(19))
wellbore_act_t (M: CHAR VARYING(16))

wellbore_activity.position_in_wellbore
Indicates the location in the wellbore of this activity.
position_in_wellbore.wellbore_activity
Indicates various activities which take place at this location along a wellbore path.
position_in_wb_s: Implements a foreign key to a row in one of the tables projected from entity position_in_wellbore depending on the value of the next column (See below).
position_in_wb_t: Defines the name of the referenced table. Possible values are defined in @position_in_wellbore.
wellbore_act_s: Implements a foreign key to a row in one of the tables projected from entity wellbore_activity depending on the value of the next column (See below).
wellbore_act_t: Defines the name of the referenced table. Possible values are defined in @wellbore_activity.