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Helpful TurboIMAGE Information
Remember the following TurboIMAGE characteristics when making changes to
data sets:
* A data set name must be unique within the database. It must be
from 1 to 16 characters long, and the first character must be
alphabetic.
* No more than 199 data sets can exist in a TurboIMAGE database.
* Data set capacity must be less than 231 -1 (2,147,483,647).
* The blocking factor is the number of entries in one block. The
default block size is 512 words, but it may have been redefined in
the schema.
* When changing the size of an entry, you should reevaluate the data
set blocking factor.
* The primary path should be the path most frequently accessed in
the data set. A data set can have only one primary path.
* Data sets can reside on different disks. The disk on which a data
set resides is the MPE XL device identified by the device class.
For heavily accessed databases, master and detail data sets should
reside on different devices.
* A field is a data item within a data set. It must be in the data
item list within the database schema.
* A search item is a field in a detail data set that defines a path
to a key item in a master data set. As many as 16 different paths
can be defined for each detail data set, but each search item can
define only one path. A master data set can be related by its key
item to as many as 16 detail data sets. Search items and key
items must be simple items; that is, their subcount must equal 1.
For more information about TurboIMAGE/XL data sets, refer to the
TurboIMAGE/XL Database Management System Reference Manual.