9. Refined Syntax

Some macros have clauses which allows syntax to be refined, specifically: the SYNTAX clause of the OBJECT-TYPE macro, and the SYNTAX/WRITE-SYNTAX clauses of the MODULE-COMPLIANCE and AGENT- CAPABILITIES macros [2]. However, not all refinements of syntax are appropriate. In particular, the object's primitive or application type must not be changed.

Further, the following restrictions apply:

                            Restrictions to Refinement on
  object syntax         range   enumeration     size    repertoire
  -----------------     -----   -----------     ----    ----------
            INTEGER      (1)        (2)           -         -
          Integer32      (1)         -            -         -
         Unsigned32      (1)         -            -         -
       OCTET STRING       -          -           (3)       (4)
  OBJECT IDENTIFIER       -          -            -         -
               BITS       -         (2)           -         -
          IpAddress       -          -            -         -
          Counter32       -          -            -         -
          Counter64       -          -            -         -
            Gauge32      (1)         -            -         -
          TimeTicks       -          -            -         -

where:

1. the range of permitted values may be refined by raising the lower- bounds, by reducing the upper-bounds, and/or by reducing the alternative value/range choices;

2. the enumeration of named-values may be refined by removing one or more named-values (note that for BITS, a refinement may cause the enumerations to no longer be contiguous);

3. the size in characters of the value may be refined by raising the lower-bounds, by reducing the upper-bounds, and/or by reducing the alternative size choices; or,

4. the repertoire of characters in the value may be reduced by further sub-typing.

Otherwise no refinements are possible. Further details on sub-typing are provided in Appendix C.