In HAMSTERS, tasks are special nodes in a hierarchical structure that can be of different types:

Task types in HAMSTERS notation
Abstract Input Output IO Processing Group

Abstract

abstract

Not Applicable

Not Applicable

Not Applicable

Not Applicable

taskgroupAbstract

User Individual

AbstractUser

perceptive

motor

homme

cognitive

taskgroup

User Cooperative

AbstractCooperativeUser

CooperativePerceptive

CooperativeMotor

hommecooperation

CooperativeCognitive

taskgroup

Interactive Individual

interactive

input

output

inout

Not Applicable

taskgroupinteractive

Interactive Cooperative

AbstractCooperativeInteractive

inputcooperation

outputcooperation

interactivecooperation

Not Applicable

taskgroupinteractive

System

AbstractSystem

output

input

inout

system

GroupSystem

Cognitive tasks can be refined in 2 subtypes (according to the Parasuraman’s model of human information processing):

  • Cognitive analysis task

    • Individual cognitive A

    • Cooperative CooperativeCognitive A

  • Cognitive decision task

    • Individual cognitive D

    • Cooperative CooperativeCognitive D

Temporal operators are used to represent temporal relationships between sub-goals and between activities:

Temporal operators
Temporal operators

Tasks can also be tagged by temporal properties to indicate whether or not they are iterative, optional or both:

Temporal properties
Temporal properties

In addition to theses qualitative aspects of the description, quantitative aspects can also be described. Tasks can be assigned an estimated minimum time and maximum time for their execution.