AcDbObjectPointer<AcDbBlockTableRecord> spBlkRec(blkRecId,McDb::kForRead);
    if(spBlkRec.openStatus() == Acad::eOk)
    {
        McDbBlockTableRecordIterator* pIterator = NULL;
        spBlkRec->newIterator(pIterator);
        if(pIterator != NULL)
        {
            std::auto_ptr<McDbBlockTableRecordIterator> spIterator(pIterator);
            for(;!pIterator->done();pIterator->step())
            {
                AcDbObjectId entId;
                pIterator->getEntityId(entId);
                AcDbObjectPointer<McDbAttributeDefinition> spAttribDef(entId,AcDb::kForRead);
                if(spAttribDef.openStatus() != Acad::eOk)
                {
                    continue;
                }

                if(spAttribDef->isInvisible() )
                {
                    continue;
                }

                // 找到一个属性定义
            }
        }
    }