  Large-scale system development companies are increasingly adopting agile
methods. While this adoption may improve lead-times, such companies need to
balance two trade-offs: (i) the need to have a uniform, consistent development
method on system level with the need for specialised methods for teams in
different disciplines(e.g., hardware, software, mechanics, sales, support);
(ii) the need for comprehensive documentation on system level with the need to
have lightweight documentation enabling iterative and agile work. With
specialised methods for teams, isolated teams work within larger ecosystems of
plan-driven culture, i.e., teams become agile "islands". At the boundaries,
these teams share knowledge which needs to be managed well for a correct system
to be developed. While it is useful to support diverse and specialised methods,
it is important to understand which islands are repeatedly encountered, the
reasons or factors triggering their existence, and how best to handle
coordination between them. Based on a multiple case study, this work presents a
catalogue of islands and the boundary objects between them. We believe this
work will be beneficial to practitioners aiming to understand their ecosystems
and researchers addressing communication and coordination challenges in
large-scale development.
