@Explain(displayName = "column name", explainLevels = { Level.USER, Level.DEFAULT, Level.EXTENDED })
  public String getColName() {
    return colName;
  }
DDL task description for ALTER TABLE ... DROP COLUMN ... command.
ql/src/java/org/apache/hadoop/hive/ql/ddl/table/column/drop/AlterTableDropColumnDesc.java