A "hammock" task is dependent on external dates for
both its start and finish dates and, ultimately, its duration. The name, hammock task, is
derived from the way a hammock's shape is determined by the distance
between the points to which it is attached.
As scheduled dates in other tasks change, the duration and start and/or
finish dates of the hammock task change as well. In other words, given
three tasks A, B, and C, task B must start on some date from task A (date
A) and task B must finish on some date from task C (date C). For an
illustration of this task B, see Example 1.
Example 1--Hammock Task B
The span of time between dates A and C dictate the available time to
accomplish task B. As Date A changes, the start date for task B changes as
well; If date C moves, task B must finish appropriately. The difference
between dates A and C is the duration for task B. See example 2.
Example 2--Date A Late, Date C Early
To build a hammock task between two other tasks, follow these steps:
- Create or determine three tasks that correspond to A, B, and C in the
example above.
- Highlight the cell that contains date A (the date that will determine
when task B starts).
- On the Edit menu, click Copy (Cell).
- Highlight the cell that contains the Start date for task B (the hammock
task).
- On the Edit menu, click Paste Special, and click Paste Link.
- Highlight the cell that contains Date C (the date that will determine
when task B finishes).
- On the Edit menu, click Copy (Cell).
- Click the cell that contains the Finish date for task B (the hammock
task).
- click Edit, click Paste Special, and click Paste Link.
Notes and Cautions
- Do not specify a predecessor for a hammock task. Only Paste Linked dates
will determine start and finish. You may specify predecessors for the
tasks from which dates are paste linked into the hammock task.
- A negative duration (finish date is before start) is not allowed.
Depending on the source of the dates, the hammock task may turn into a
milestone (zero duration) or erroneously calculate duration before the
finish date or after the start date.
- An OLE update is different from a calculation. You may not see expected
changes in the hammock task after calculating project. From the Edit
menu, click Links to edit/update OLE links (Paste Links). Alternatively,
press the F9 function key twice.
- Because the hammock task relies on other tasks for start/finish
information, anything that affects those other tasks (resource leveling,
constraints) will ultimately affect the hammock tasks dates.
- If the hammock task is a child to a summary task, it may inherit
predecessor behavior from the summary task that may affect its duration
and/or start and finish dates or create a circular relationship.
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