Page (File architecture)

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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 following:

  • The file name, which is the name used in the create process.
  • The date/time when the individual 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, the numeric representation for which is as follows:
    TableNumber
    FCT00
    Table A01
    Table B02
    Table C03
    Table D04
    Table E40
    Table X20
  • The sequential page number within the table; a three-byte binary integer.

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