9.3.2 Modules
A property set definition is divided into named modules each described by a psmodule element.  The attributes have the following meaning:

•  rcsnm gives the RCS name of the module.

•  fullnm gives the full name.

•  dependon lists the names of the modules on which this module depends.

•  required specifies whether the module is required, that is, shall be included in every grove plan. A value of required means that it is required; a value of nrequire means that it is not. The default is nrequire.
Including a module in a grove plan is equivalent to including in the grove plan:

•  all the classes and properties defined within the module,

•  any modules on which the module depends, and, recursively, any modules on which they depend.
In addition to modules defined in property sets, there are a number of intrinsic modules defined in this International Standard that are automatically part of every property set.  Properties defined in intrinsic modules are called intrinsic properties. Intrinsic modules are treated as occurring before all non-intrinsic modules.