A limit or restriction on the times at which two activities may occur in a specified schedule. The constraints may describe the future (and constrain two planned activities) or the past (implying the times of actual activities were constrained). For example, assembly could not start until the components were delivered.

schedule_cstr_s (PK, M: CHAR VARYING(19))

Surrogate key of the table.


constraint_for_s (FSK, M: CHAR VARYING(19))
constraint_for_t (M: CHAR VARYING(16))

schedule_constraint.constraint_for
Gives the activity that is constrained by this schedule constraint.
constraint_for_s: Implements a foreign key to a row in one of the tables projected from entity activity depending on the value of the next column (See below).
constraint_for_t: Defines the name of the referenced table. Possible values are defined in @activity.


r_schedule_cstr_nm (FNK, M: CHAR VARYING(40))

schedule_constraint.ref_schedule_constraint
The constraint kind, describing the logical condition of the constrained activity with respect to either the constraining activity or absolute time. Examples are: start of constrained activity leads the end of the constraining activity by relative time; start of constrained activity lags absolute time by relative time.
Defines a foreign key to table r_schedule_cstr.


schedule_s (FSK, M: CHAR VARYING(19))

schedule_constraint.schedule
Gives the schedule that the schedule constraint is valid for. A schedule constraint is only valid for one schedule.
Defines a foreign key to table schedule.


absolute_time (O: TIMESTAMP)

schedule_constraint.absolute_time
A reference to a calendar date and clock time, constraining the time at which the constrained activity of the schedule constraint may be scheduled. The type of constraint using the absolute time value is given by the constraint kind.


activity_duration (O: DAYTIMEINTERVAL)

schedule_constraint.activity_duration
The duration of the constrained activity of the schedule constraint. This may act as an upper limit, a lower limit or both. The limit type is specified by the constraint kind.


description (O: CHAR VARYING(2000))

schedule_constraint.description
A description of the schedule constraint.


relative_time (O: DAYTIMEINTERVAL)

schedule_constraint.relative_time
The time interval between the constrained activity and either the constraining activity or the absolute time for the schedule constraint. The role of the time interval is given by the constraint kind.


constrained_by_s (FSK, O: CHAR VARYING(19))
constrained_by_t (O: CHAR VARYING(16))

schedule_constraint.constrained_by
This activity acts as a constraint, via the schedule constraint, upon the other activity related to this schedule constraint.
constrained_by_s: Implements a foreign key to a row in one of the tables projected from entity activity depending on the value of the next column (See below).
constrained_by_t: Defines the name of the referenced table. Possible values are defined in @activity.