Reading Blobs with CFRONT

Does anybody knows how can you read blobs using CFRONT. If blobs are stored in a different area of the table… what do you receive when you get the address of the data using DBL_GetFieldDataAddr(). And since each blob contains 4 extra bytes beside the sife of the blob itself… what are they… what they mean. Thanks

By DBL_GetFieldDataAddr() you get a pointer to BLOB. You can use it as array. Where you finding these 4 extra bytes ?