Page (File architecture)

A page is the underlying structure applied to the data sets that comprise a Model 204 file.

All pages are 6184 bytes.

When a file is created, the pages in the file are formatted into:

• 6144 bytes of 'usable' space (how the space is used depends on the table where the page resides)
• a 40 byte page trailer

The page trailer

The page trailer contains:

• the file name, which is the name used in the create process
• the date / time when the page was last initialized
• the date / time when the page was last written to the file
• data used in the checkpoint process
• the table that this page is part of (a numeric representation as explained in Note 1 below)
• the sequential page number within the table

Note 1: FCT = 00, Table A = 01, Table B = 02, Table C = 03, Table D = 04, Table E = 40 and Table X = 20.

Because of INCREASE and DECREASE commands after the initial CREATE, the pages for a table may not be contiguous.