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Structure of pages Data page
U929-J-Z125-9-76 217
Dokuschablonen 19x24 Version 7.3us für FrameMaker V7.x vom 14.02.2007 © cognitas GmbH 2001-2007
18. Oktober 2007 Stand 11:29.50 Pfad: G:\vogt\fsc\uds\Manuale\en\udsent_e\udsent.k07
Meanings of bytes 1-28 or 1-32
There is a page index entry for each record and each table in the page, indicating the
position of the record or table. In the case of lists, there is a page index entry for the list itself
and for every record contained in it. The logical sequence of records in a list is not based
on their physical sequence, but on the sequence of the page index entries.
A data page must not contain two anchor records at the same time.
Byte Meaning
1-4 contains the address of the page.
13-16 specifies the length and the beginning of the free space. Since the free space
is filled with records and tables starting at the end of the page, the beginning of
the free space borders on the last stored record or table.
This information on free place represents the second level of the UDS/SQL
three-level Free Place Administration facility.
17-18 contains the number of page index entries.
19-20 The page length may be 2048 bytes, 4000 bytes or 8096 bytes.
Record Table
21-24
or
21-28
Database key value of the record Database key value of the associated
owner record
25/29 DBTT column=0 DBTT column=1-n
26/30 Status=0: Record is not part of a list
(anchor record)
Status=2: Record is part of a list
Status=1
27-28
or
31-32
indicates the beginning of the record or table.
Table 19: Meanings of bytes 1-28 or 1-32 of a data page