TurboIMAGE/XL Database Management System Reference Manual MPE/iX V6.5 (30391-90011)

Chapter 5 209
TurboIMAGE/XL Library Procedures
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Table 5-16. Lock Descriptor Fields
Field Name Description
length A halfword integer specifying the physical length in halfwords of the lock
descriptor, including the length field itself.
dset Describes the data set in which locks are placed. It is always 8 halfwords long and
can be one of the following:
• A data set name, left-justified, 16 characters long or, if shorter, terminated
with a blank or semicolon (for example, SALES;).
• A data set number, an integer in the range of 1 to 199 stored in the first
element.
• An at-sign (@) stored in the first byte of the dset and a lock descriptor length of
2 indicating that the whole database is to be locked. All unused bytes are
ignored. In this case, the ditem, relop, and value fields are ignored and can be
omitted if desired.
• A blank or semicolon (first byte) or binary zero (first halfword) indicating that
the whole lock descriptor is to be ignored. (It is counted as one of the n
descriptors.)
The data set, if specified, need not be accessible for read or write access to the user
requesting the lock.
ditem Always 8 halfwords long unless an @ is stored in the first byte. It can be one of the
following:
• A data item name, left-justified, 16 characters long or, if shorter, terminated
with a blank or semicolon.
• A data item number stored as an integer in the first halfword. It can be in the
range of 1 to 1023.
• An at-sign (@) stored in the first byte of the ditem indicating that the whole
data set specified in dset is to be locked. All unused bytes are ignored and can
be omitted if desired.
The data item need not be a search item, nor does it have to be accessible to the
user requesting the lock. However, it cannot be a compound item or a P-type item
longer than P28.
relop One halfword long, it contains one of the three relational operators represented as
two ASCII characters:
<= less than or equal
>= greater than or equal
= or = equal ( indicates space character)
value The value of the data item to be locked. It must be stored in exactly the same way
as it is stored in the database. TurboIMAGE/XL extracts as many halfwords as
required by the corresponding data item definition (in the schema). The rest (if
any) are ignored.