The method in which records are physically stored in a specified order according to a keyfield in each record is all of the above direct sequential hash.

The method in which records are physically stored in a specified order according to a keyfield in each record is called Sequential.

In a sequential file organization method, records are stored based on the key field value. This method is simple and efficient when we have a small amount of data, but as data grows, the time taken to access records will increase.

Here's a step-by-step explanation:

1. Each record in the file has a unique key field which acts as an identifier for the record.

2. The records are stored in a sequence based on the key field. This sequence can be ascending or descending.

3. When a new record is inserted, it is placed in the correct sequence based on its key field.

4. When a record needs to be accessed, the system starts from the beginning of the file and goes through each record until it finds the one it needs. This can be time-consuming if there are a lot of records.

5. If a record needs to be deleted, the system will find the record and then rearrange the remaining records to keep the correct sequence.

6. The main advantage of this method is that it is simple to understand and implement. The main disadvantage is that it can be slow to access records, especially if the file is large.