!!Handling of simulation parameters ([@c]add, [@c]remove, [@c]list)

Simulation parameters are organized in a file system directory tree, the so
called results tree. The values of one simulation parameter are located in
exactly one height of the results tree. Values for simulation parameters may be
added or removed by SimTree. Each tuple of exactly one value for each simulation
parameter is called a simulation parameter value set.

Each simulation parameter has an associated date type which is one of int,
float, bool or string. The type of a simulation parameter is defined when the
simulation parameter is added to the results tree.

The selection of the simulation parameters value sets which a command should use
is done with a sequence of --simulation-parameter options. When no
[@o]--simulation-parameter option is given, the default of sets used depend on the
kind of operation:

* For operations which add something to the results tree ([@c]add,
  [@c]simulate, [@c]collect), all sets in the tree are used.
  
* For operations which remove
  something from the tree ([@c]remove, [@c]clean), per default no set is used, so the
  operation does nothing when no [@o]--simulation-parameter option is given. In this
  case, the option [@o]--force-all-values selects all sets in the tree.

%inc parts simulation-parameter-option-ordering

With a sequence of [@o]--simulation-parameter options also a subset of values may
be selected. When used without values after the simulation parameter name, the
meaning of the omission depends on the operation: For adding operations, all
values for the corresponding parameter are selected. For removing operations no
value is selected. Again, in the latter case the [@o]--force-all-values option may
be used to reverse the meaning for removing operations. The option
[@o]--simulation-parameter-path may be used to abbreviate the selection of
parameter value sets.
