EMS Manual

EMS Definitions
EMS Manual—426909-005
14-2
Header Tokens Overview
either header or data-portion tokens by calls to the EMSGET or EMSGETTKN
procedures. For information, see EMSGET and EMSGETTKN Procedures on
page 15-12.
Header Tokens Overview
Event-message header tokens represent values that occur in every event message.
These tokens are prefixed by either ZEMS or ZSPI.
Header tokens are shared by all subsystems. That is, header token codes have the
same values in every subsystem, and these values do not overlap the values of tokens
that are private to a subsystem.
Therefore when you call EMSGET or EMSGETTKN to get the value of a header token,
you can omit the ssid parameter. The header token is recognized regardless of the
default subsystem ID.
Similarly, when you reference a header token in a filter specification, you do not need
to qualify the token name, no matter what the default subsystem ID is at the place of
reference.
Header Tokens Usage Restrictions
You cannot perform most EMSGET special operations, such as the ZSPI-TKN-ADDR
and ZSPI-TKN-NEXTTOKEN operations, on header tokens. The ZSPI-TKN-LEN and
ZSPI-TKN-COUNT operations are the only special operations defined for header
tokens.
These restrictions are because the values of header tokens are stored in the buffer
without their token codes in a compact form that is private to HP.
For information about special operations, see EMSGET and EMSGETTKN Procedures
on page 15-12.
Event Message Requirements and Conventions
Knowing these conventions can help you retrieve event-message information in an
application or help you examine event messages with a filter:

To retrieve information from event messages, use only EMS procedures (and
certain SPI procedures). For more information, see Section 15, EMS Procedures
.

An event message can contain an error list or a series of error lists, any of which
can be nested. For information on how to retrieve tokens within a list, see the SPI
Programming Manual.

Event messages cannot be nested.

The ZEMS-TKN-ACTION-NEEDED token used with the ZEMS-TKN-ACTION-ID
token can help you coordinate related events. For information on the use of these
tokens, see Section 8, Reporting Events.