Subject: Re: "Once" is not enough :-)

From: Paul Long <[email-masked]>
Date: Sat, 27 Jan 2001 14:05:05 -0600

Okay, I'll try again. This time I am concerned about the modemType ABNF
construct. The accompanying comment says, "at-most-once," and then several
alternatives are listed for modemType, all of which are simple tokens except
extensionParameter. I'm 99% sure that the at-most-once comment doesn't
really apply to this last alternative proper but rather means that each
_value_ of extensionParameter may appear only once but that
extensionParameter itself may occur multiple times, in the same way as
propertyParm is treated in my previous email. Is this correct?

Paul Long
ipDialog, Inc.

-----Original Message-----
From: Media Gateway Control (megaco)
[mailto:[email-masked]]On Behalf Of Paul Long
Sent: Sunday, December 31, 2000 4:33 PM
To: [email-masked]
Subject: Re: "Once" is not enough :-)

Here a specific problem I'm having in this area.

Regarding this ABNF from RFC3015:
        terminationStateDescriptor = TerminationStateToken LBRKT
terminationStateParm *( COMMA terminationStateParm ) RBRKT
        ; at-most-once per item
        terminationStateParm =(propertyParm / serviceStates /
eventBufferControl )

I assume the comment means that, for example, ServiceStates cannot be
specified as both Test and OutOfService and that Buffer cannot be both OFF
and LockStep. That's pretty straightforward; however, does it mean that only
one propertyParm can be specified or that only one propertyParm per
package/item identifier combination can be specified? IOW, I assume that
this is illegal
        PkgA/ItmA=3, PkgA/ItmA=6
but is the following also illegal?
        PkgA/ItmA=3, PkgA/ItmB=8
The comment isn't at all clear, IMO.

Paul Long
ipDialog, Inc.

-----Original Message-----
From: Media Gateway Control (megaco)
[mailto:[email-masked]]On Behalf Of Paul Long
Sent: Sunday, December 31, 2000 12:33 PM
To: [email-masked]
Subject: "Once" is not enough :-)

1. Regarding this idiom:
        y = x *x

        ; at-most-once
        x = a / b / c / d

Doesn't the comment refer to the use of x in y rather than x by itself? I
say this because x can only take on one of the alternative values at a time.

2. Are the these comments equivalent?
        ; at-most-once
        ; at-most-once per item
        ; at-most-once of each
        ; at-most-once each of x, y, z
        ; every x at most once

3. Does "exactly once x" mean that x is required and there cannot be
multiple occurrences of x?

Paul Long
ipDialog, Inc.

---

From: Christian Groves <[email-masked]>
Date: Mon, 29 Jan 2001 12:07:42 +1100

G'Day Paul,

Yes this is correct. I'll update the implementors' guide to reflect this
as per the other at most once changes.

Cheers, Christian