When five or more records get accumulated for a particular correspondent then alphabetic file is transferred to numbered file.
Explanation:
Numbered file is the classification of records where they are arranged in numbers. Records in this file are arranged in ascending order starting from smallest to largest.
Numbered file system is used wherever there is requirement to store and retrieve huge amount of records, and also where there is requirement of more confidentiality.
Alphabetic file keeps a record of correspondents whose volume is very low and also those which have not yet been assigned numbers.
The general alphabetic file is always placed before numbered file. The main reason for this is that alphabetic file stores small number of correspondents. Once number increases they are moved to numbered files. Also, expansions are always allowed at the end.
