The
ERDS header record provides the following
information to the system recording routines about the device on which
the ERDS resides:
- Where to write new records
- When the data set is getting full
The tables in this topic show the header records for each system.
The terms used in the table headings are described below:
- Offset
- Is the numeric address of the field relative to the beginning
of the data area.
- Dec(hex)
- Is the offset in decimal, followed by the hexadecimal equivalent
in parentheses. For example: 16(10).
- Size (bytes)
- Is the field size in bytes.
- Alignment (bits)
- Shows the bit settings of switch or flag fields, as follows:
- .... ....
- Indicates the eight bit positions (0–7) in a byte. For
ease of scanning, the high-order (left-hand) four bits are separated
from the low-order four bits.
- x... ....
- Is a reference to bit 0.
- 1... ....
- Indicates that bit 0 is on.
- 0... ....
- Indicates that bit 0 is off.
- .... ..xx
- Is a reference to bits 6 and 7.
The record mappings include significant bit settings. Bits described
as reserved are not significant for this release.
- Field Name
- Is a label (acronym) that identifies the field.
- Description
- Indicates how the field is used:
- Where the field’s use relates directly to a value you would
code, the coded value is shown.
- Where the hexadecimal code for a particular bit setting may be
helpful, it is shown separated from the rest of the description.