iX V6.5 (30391-90011)

66 Chapter3

Deﬁning a Database

Item Part

depends upon the type designator and can be a halfword,abyte,oranibble. A halfword

is 16 bits, a byte is eight bits, and a nibble is four bits or a half-byte.

NOTE

In this manual, a word is a 32-bit storage unit and a halfword is a 16-bit

storage unit. One byte is 8-bits.

Table 3-2. describes the type designators and the unit of measure used for each.

A data item must be an integral number of halfwords in length regardless of the type

designator and its unit of measure. In other words, data items of type P, which are

measured in nibbles, must have a sub-item length and sub-item count such that their

product is evenly divisible by 4, because 4 nibbles equal 1 halfword. Data items of type U,

X, or Z, which are measured in bytes, must have a sub-item length and sub-item count

such that their product is an even number. If a data item is deﬁned as U3, it cannot be a

simple item and must have an even numbered sub-item count so that the data item length

is an integral number of halfwords.

A data item cannot exceed 2047 halfwords in length. The entire item, whether simple or

compound, is always handled as a unit by TurboIMAGE/XL.

TurboIMAGE/XL and Program Language Data Types

The type designator, sub-item count, and sub-item length you specify for a data item

deﬁnes its length. TurboIMAGE/XL does not perform any conversions of data or examine

the item to check its validity as it is being added to the database. The only data item

values that TurboIMAGE/XL checks are those speciﬁed as part of a lock descriptor in calls

to the DBLOCK procedure. Refer to the discussion on DBLOCK in chapter 5. There are no rules

requiring that a speciﬁc type of data deﬁned by a programming language must be stored in

Table 3-2. Type Designators

Unit Bits Type\

Designator

Description

Halfword 16-bit E A real (IEEE ﬂoating point) number.

I A signed binary integer in 2's complement form.

J Same as I, but QUERY/3000 allows only numbers

conforming to speciﬁcations for COBOL II

COMPUTATIONAL data to be entered.

K An absolute binary quantity (no negative values).

R A real (HP 3000 ﬂoating point) number.

Nibble 4-bit P A packed decimal number.

Byte 8-bit U An ASCII character string containing no lowercase

alphabetic characters.

X An unrestricted ASCII character string.

Z A zoned decimal format number.