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Capability: A capability is some desired skill or ability that a participant may
possess. For example, first aid skills, health and safety training, a forklift license,
or a second language may all be considered as capabilities that a participant may
possess that may be useful to an organization. There may be several participants
within an organization possessing the same capability, and a certain participant
may possess a number of capabilities. In the YAWL model, a participant may
possess zero or more capabilities. A capability (or capabilities) may be included
in a filter defined at design time that is run over the distribution set for a task
at runtime, meaning that only those participants within the distribution set that
possess the specified capability or capabilities are to be considered as potential
recipients of a work item created from the task.
Position: A position typically refers to a unique job within an organization
for the purposes of defining lines-of-reporting within the organizational model.
Examples might include CEO or Bank Manager, or may be internal job codes
(such as “TEL0123”). Although generally a participant will hold exactly one
position, and each position in the model will contain exactly one participant,
to maximize flexibility these restrictions are not enforced in the YAWL model;
within YAWL, a participant may hold zero or more positions. Importantly, a posi-
tion may report to zero or one other positions (e.g., bank teller “TEL0123” may
report to the Bank Manager), and may belong to zero or one Org Groups (see
below). Like capabilities, a position (or positions) may be included in a filter
defined at design time that is run over the distribution set for a task at runtime.
Positions are also used at runtime to enable resource patterns such as delega-
tion, reallocation, and viewing of team work queues (see Sect. 10.7 for more
details).
Org Group: An organizational group (org group) is a functional grouping
of positions. Common examples might include Marketing, Sales, Human
Resources, and so on, but may be any grouping relevant to an organization. In
the YAWL model, each position may belong to zero or one org groups. Further,
like roles, an org group may belong to a larger, more general org group (e.g.,
the groups Marketing and Sales may each belong to the more general Production
group). Org groups are often also based on location. Like positions, org groups
may be included in a filter defined at design time that is run over the distribution
setfor atask atruntime.

While the descriptions of the various entities in the YAWL model above discuss
the typical uses of each, it should be clear that they represent, at the most basic
level, merely various ways to group participants. Therefore, they can equally be
used to assemble participants into any kinds of groupings that are meaningful to the
implementing organization. The main point of distinction between them is that only
roles can be used to populate a distribution set, the other three are used to perform
restrictions over the set.