Construct an OccurrenceInfo object that describes a command-line option that is optional but not hidden (i.e., `e_OPTIONAL == occurrenceType()`) and has no default value. Optionally specify a basicAllocator used to supply memory. If basicAllocator is 0, the currently installed default allocator is used.
Declared in <balcl_occurrenceinfo.h>
OccurrenceInfo();