All stimulation devices share the parameters ``start`` and ``stop``,
which control the stimulation period. The property ``origin`` is a
global offset that shifts the stimulation period. All three values are
set as times in ms.

- For spike-emitting devices, only spikes with times `t` that fulfill
  :math:`\mathrm{start} < t \leq \mathrm{stop}` are emitted. Spikes
  that have timestamp of :math:`t = \mathrm{start}` are not emitted.

- For current-emitting devices, the current is activated and
  deactivated such that the current first affects the target dynamics
  during the update step :math:`(\mathrm{start}, \mathrm{start}+h]`,
  that is, an effect can be recorded at the earliest at time
  :math:`\mathrm{start}+h`. The last interval during which the current
  affects the target's dynamics is :math:`(\textrm{stop}-h, \textrm{stop}]`.

The property ``stimulus_source`` defaults to an empty string. It can
be set to the name of a stimulation backend, in which case it will
take its parameters from the configured backend instead of from the
internally stored values. More details on available backends and their
properties can be found in the :ref:`guide to stimulating the network
<sec_stimulation_backends>`.

Parameters
++++++++++

label
    A string specifying an arbitrary textual label for the device.
    Stimulation backends might use the label to generate device specific
    identifiers like filenames and such. Default: ``""``.

origin
    A positive floating point number used as the reference time in ms
    for ``start`` and ``stop``. Default: ``0.0``.

start
    A positive floating point number specifying the activation time in ms,
    relative to ``origin``. Default: ``0.0``.

stimulus_source
    A string specifying the name of the stimulation backend from which to
    get the data for updating the stimulus parameters of the device.
    By default, the device uses its internally stored parameters for updating
    the stimulus. Default: ``""``.

stop
    A floating point number specifying the deactivation time in ms, relative
    to ``origin``. The value of ``stop`` must be greater than or equal to
    ``start``. Default: ``infinity``.