Why are object names limited to 10 chars long?

Ravi,

As others have pointed out, table/file names can be larger than 10 bytes
by way of DB2/400 extensions.  But as you did ask "or any object name
for that matter" I tried to do some historical digging.  This is the
result of some of that digging.

First object names are really 30 bytes in length at the Machine Interface
(MI), so a reasonable starting question is "why does OS/400 (and the S/38
CPF) only externalize 10 byte names for objects?"  The one answer most
seem to agree on is that there was a general feeling back in the early
1970s (definitely prior to 1975) to support a 3 level name qualification.
One example of such qualification might be Database member names being
the concatenation of file, library, and member (though Database is quick
to point out that this is NOT the implementation of member objects so
don't blame them for 10 byte names :-)).  So if the Machine provided 30
byte names, and the OS desired the ability for 3 level qualifying, the
conclusion would be to provide 10 byte external names (from an OS
perspective).  Perhaps as a rationalization, 10 byte names also provided
sufficient space on the green screen panels of the day to also provide
textual descriptions, etc. which would have been greatly decreased if
panels had to reserve 30 bytes for names.

As for the 10 byte restriction being a carry over from RPG, we can
certainly say "no".  RPG has historically allowed on 8 bytes for file
names (as any RPG coder with a 10-byte file name can testify to).

Bruce Vining

>
>...Why is the file name or any object name for that matter limited to 10
>chars on the 400? When Windows went to 32 bit, longer file names were
>allowed.  Has the 10 char restriction been carried over from the old
>days because of RPG restrictions? Can someone shed some light on this??
>
>Thanks in advance....
>
>Ravi
>

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