Definition Attributes
Data Definition Language (DDL) Reference Manual — 426798-002
6- 36
SPI-NULL Clause
•
If SPI-NULL is not specified, the default SPI null value is 255; that is, SSNULL sets
all bits to 1.
•
An explicit SPI-NULL clause for a field or for a group containing the field overrides
the default SPI null value.
•
You should not specify a VALUE clause for a field or group used to define an
extensible structured token. Every field in an extensible structured token is
initialized to its SPI null value before it is used, so any initial value is overwritten.
If the field is used for other purposes, then you can specify a VALUE clause as well
as an SPI-NULL clause. In this case, the field is not initialized to its SPI null value
but is given the specified initial value. Because an initial value and an SPI null
value are never used for the same purpose, they need not be the same value.
•
An SPI-NULL clause specified in a group definition, or in a group description within
a group definition, is inherited by each of the fields within the group that has the
clause. A field within a group defined with an SPI-NULL clause cannot have its
own SPI-NULL clause.
•
When you refer to one definition from another, the following applies:
°
If you specify an SPI-NULL clause in the referring definition or in any group
that includes the referring definition, the specified SPI null value overrides all
SPI null values in the referenced definition.
°
If you do not specify an SPI-NULL clause in the referring definition, the
referring definition inherits the SPI null value of the referenced definition.
SPI-NULL Clause Examples
You can specify the SPI-NULL clause for a single field, like this:
DEF assn-ddl-jobcode TYPE BINARY 16 SPI-NULL 0.
You can also specify the SPI-NULL clause for a group of fields, like this:
If the SPI-NULL clause is omitted from an extensible structured token, the default SPI
null value is 255. For example:
DEF assn-ddl-jobinfo SPI-NULL 1 .
02 jobcode TYPE BINARY 16 .
02 priority TYPE BINARY 16 .
END .
Inherits SPI null value 1 .
Inherits SPI null value 1 .
VST607.vsd
DEF assn-ddl-jobcode TYPE BINARY 16 .
Default SPI null value is 255.
VST608.vsd