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Helpful TurboIMAGE/XL Information
Remember the following TurboIMAGE/XL characteristics when making changes
to data items:
* A data item 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 1023 data items can exist in a TurboIMAGE/XL
database.
* Valid data item types for TurboIMAGE/XL are E, I, J, K, P, R, U,
X, and Z. For data item type conversion information, refer to
Table 2-1 .
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NOTE Data type E can be specified with an optional exclamation
point (!E). This is a special version of the E data type and
is also known as the no-conversion option. It indicates
that the data is already in IEEE data format and should not
be converted; only the type specifications should be
changed. If the item length is changed, the data is
converted to the new length but is still assumed to be in
IEEE format.
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* The unit of measure for data item length depends upon the type
designator and can be a halfword, a byte, or a nibble. A halfword
is 16 bits, a byte is 8 bits, and a nibble is 4 bits or a half
byte.
* A data item cannot exceed 2047 halfwords in length and must be an
even number of bytes.
* The subitem count must be an integer from 1 to 255. For item type
P, the subitem count multiplied by the item length must be evenly
divisible by 4. For item types U, X, and Z, the subitem count
multiplied by the item length must be an even number.
* The subitem length must be from 1 to 255, depending on the type
designator as follows:
|
Type | Length
|
-----------------------------------------------------------------------------------------
|
E, R | Must be 2 or 4 halfwords.
|
I, J | Must be 1, 2, or 4 halfwords.
|
K | Must be 1 or 2 halfwords.
|
P | Maximum is 255 nibbles.
|
U, X, Z | Maximum is 255 bytes.
|
* A compound data item is a data item with a subitem count of more
than one. Search and sort items cannot be compound items.
When changing data item length, reevaluate the blocking factor of the
sets containing the items.
For more information about TurboIMAGE/XL data items, refer to the
TurboIMAGE/XL Database Management System Reference Manual.