A file whose organization uses an
index. The index may be
separated from the file, as in the case of a book, or located within the file,
as in the case of a telephone directory. An index may be based upon the data
item on which the file is ordered, if the file is sequential. In this case it is
usually called a primary index and the file is called an indexed sequential
file. Alternatively, the index may be upon a data item that is not the one used
for ordering and in that case it is known as a secondary index.
See also file
organization.
