There has been some discussion here about what a subtype is
(under the 'enum inheritance' thread).

FYI, here is an interesting definition:

"A subtype is a datatype derived from an existing datatype,
 designated the base datatype, by restricting the value space to a subset
 of the base datatype whilst maintaining all characterizing operations".

The definition appears in ISO/IEC DIS 11404, which is the Draft International
Standard for Language Independent Datatypes.


--
        JOHN (MAX) SKALLER,         INTERNET:maxtal@suphys.physics.su.oz.au
 Maxtal Pty Ltd,      CSERVE:10236.1703
        6 MacKay St ASHFIELD,     Mem: SA IT/9/22,SC22/WG21
        NSW 2131, AUSTRALIA