Before the reserved
project, there may be one or two "qualifiers", that
is identifiers or other reserved words, to qualify the project.
The current list of qualifiers is:
abstract: qualify a project with no sources. A qualified abstract
project must either have no declaration of attributes
Source_List_File, or one of
Languages must be declared
as empty. If it extends another project, the project it extends must also be a
qualified abstract project.
standard: a standard project is a non library project with sources.
aggregate: for future extension
aggregate library: for future extension
library: a library project must declare both attributes
configuration: a configuration project cannot be in a project tree.