SUCCESSOR Statement
SUCCESSOR variables / lag options ;
SUCC variables / lag options ;
The SUCCESSOR statement is required when data are
input in an AON format. This statement
specifies the variables that contain the
names of the immediate successor nodes (activities)
to the ACTIVITY node. These variables must be of the same type
and length as those defined in the ACTIVITY statement.
If the project does not have any precedence relationships, it is
not necessary to use the SUCCESSOR statement. Thus, you can
specify only the ACTIVITY statement
without an accompanying SUCCESSOR statement.
If the precedence constraints among the activities have some
nonstandard relationships, you can specify these using the LAG options.
The following is a list of LAG options.
-
ALAGCAL= calname
-
specifes the name of the calendar to be used for all lags. The default
value for this option is the DEFAULT calendar.
-
LAG=variables
-
specifies the variables in the Activity data set used to identify the
lag relationship (lag type, duration, and calendar) between the activity
and its successor. The LAG variables must be character variables.
You can specify as many LAG variables as there are SUCCESSOR variables;
each SUCCESSOR variable is matched with the corresponding LAG variable.
You must specify the LAG variables enclosed in parentheses.
In a given observation, the ith LAG variable specifies
the type of relation between the current activity (as specified by the
ACTIVITY variable) and the activity specified
by the ith SUCCESSOR
variable. If there are more LAG variables than
SUCCESSOR variables, the extra LAG variables are ignored; conversely,
if there are fewer LAG variables, the extra SUCCESSOR variables are all
assumed to indicate successors with a
standard (finish-to-start)
relationship.
In addition to the type of relation, you can also specify
a lag duration and a lag calendar in the same variable. The
relation_lag_calendar information is expected to be specified as
keyword _ duration _ calendar
where keyword is one of ' ', FS, SS, SF, or FF,
duration is a number specifying the
duration of the lag (in interval
units), and calendar is either a calendar name or number
identifying the calendar followed by the lag duration. A missing
value for the keyword is assumed to mean the same as FS,
which is
the standard relation of finish-to-start.
The other three values, SS, SF, and FF, denote
relations of the type start-to-start,
start-to-finish, and
finish-to-finish, respectively.
If there are no LAG variables, all
relationships are assumed to be of the type
finish-to-start with
no lag duration.
Table 2.19 contains some examples of lag specifications.
Table 2.19: Lag Specifications
| Activity | Successor | LAG | Interpretation |
|---|
| A | B | SS_3 | Start to start lag of 3 units |
| A | B | _5.5 | Finish to start lag of 5.5 units |
| A | B | FF_4 | Finish to finish lag of 4 units |
| A | B | _SS | Invalid and ignored (with warning) |
| A | | SS_3 | Ignored |
| A | B | SS_3_1 | Start to start lag of 3 units w.r.t. calendar 1 |
-
NLAGCAL= calnum
-
specifes the number of the calendar to be used for all lags. The default
value for this option is the DEFAULT calendar.
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.
