Different sub-processes
can be assembled into a full chain, when the end of the foregoing sub-process
matches the needs of the following sub-process. In the functiogram, such a
so-called ‘buffer’ is symbolized by a dark button.
In real
life, when we plan any job, we know where it begins and where it should end.
Between these two poles we have a lot of options to reach this aim. But as soon
as we define one specific sub-process, the list of viable sub-processes becomes
much shorter.
For
example, we want to fell trees and process them into short logs, which are
stored at the forest road. This means that we start with buffer 10 and end up
at buffer 33. Here we have more than 5 options to reach this goal. But when we decide
to use a forwarder for the extraction tasks, the degree of freedom decreases,
because the forwarder is specialized for extraction from 23 to 33 (it is good
for short logs). To finalize the method, we only need to fill the gap between
buffers 10 and 23. Then, out of our initial more than 5 options, only 3 are
left.