The fields of the BooleanClause.Occur class are listed below. For a complete list of BooleanClause.Occur class members, see the BooleanClause.Occur Members topic.
Public Static Fields
  MUST | Use this operator for clauses that must appear in the matching documents. |
| MUST_NOT | Use this operator for clauses that must not appear in the matching documents. Note that it is not possible to search for queries that only consist of a MUST_NOTclause. |
| SHOULD | Use this operator for clauses that should appear in the matching documents. For a BooleanQuery with no MUSTclauses one or more SHOULDclauses must match a document for the BooleanQuery to match. |
See Also
BooleanClause.Occur Class | Lucene.Net.Search Namespace