Distributed Name Service (DNS) Management Programming Manual

Glossary
46958 Tandem Computers Incorporated Glossary–19
Token code. In SPI, a variable or variable name that represents a simple token or a
special operation. A token code is implemented as a 32-bit number consisting of a
token type and a token number. Compare Token map. In DDL, a special definition
(using the TOKEN-CODE statement) that the DDL compiler will translate into an SPI
token code.
Token data type. The part of the token code that defines the kind of value (such as an
integer or a file name) allowed for a token.
Token length. The part of a token code that indicates the length, in bytes, of the
corresponding token value. A token length of 255 indicates that the token value has
variable length or a length greater than 254; in this case, the first word of the token
value contains the (noninclusive) byte length of the rest of the token value.
Token map. In SPI, a variable or variable name that represents an extensible structured
token. The token map includes the token type, the token number, and a description of
the token value: its fields, the null values of those fields, and the versions of the fields.
A token map defines a structure that might change in some later code version (by the
addition of new fields at the end), and the information in the map allows SPI to
provide compatibility between different structure versions. Compare Token code. In
DDL, a special definition (using the TOKEN-MAP statement) that the DDL compiler
will translate into an SPI token map.
Token number. The number used by a subsystem to identify a token. The token type
and the token number together form the token code.
Token-oriented. An attribute of a programmatic interface that conveys information as a
series of code-value pairs accessed by code, rather than by address or ordinal position.
SPI is a token-oriented programmatic interface.
Token type. In SPI, a combination of the token data type and token length—part of the
token code; in DDL, a special definition (using the TOKEN-TYPE statement) the DDL
compiler will translate into an SPI token type.
Token value. The value assigned to a token.
Type. See Alias type, Subsystem-object type, and Composite type.
Type number. See Alias type number, Subsystem-object type number, and Composite
type number.
Type name. See Alias type name, Subsystem-object type name, and composite type
name.
Typed alias. An alias with a type attribute, used in an application where it is required to
distinguish between multiple aliases for the same object.
Untyped alias. An alias with no type attribute, used in an application where it is
unnecessary to distinguish between multiple aliases for the same object.
Upward compatibility. The ability of a requester to operate gracefully with a server of a
higher revision level. In this case, the requester is upward-compatible with the server,
and the server is downward-compatible with the requester. Compare with
Downward compatibility.