Mike

Not true, the constraint that %ES; can never appear as part of any other token is already encapsulated in the grammar syntax for entities in 6.3.1.2.

I'm not bothered about the WSP restrictions, it's clear what the effect of the token is.

Regards

Steve Hanson

IBM Hybrid Integration, Hursley, UK
Architect, IBM DFDL
Co-Chair, OGF DFDL Working Group
smh@uk.ibm.com
tel:+44-1962-815848
mob:+44-7717-378890
Note: I work Tuesday to Friday

From: Mike Beckerle <mbeckerle.dfdl@gmail.com>
To: DFDL-WG <dfdl-wg@ogf.org>
Date: 06/09/2019 21:14
Subject: [DFDL-WG] clarifications needed for %ES; and %WSP*; entities
Sent by: "dfdl-wg" <dfdl-wg-bounces@ogf.org>

Currently, we have gaps in the spec. E.g., in discussion of dfdl:initiator, the spec says %ES; cannot appear alone in the list, but there is nothing prohibiting one from just using
dfdl:initiator="%ES;%ES;" or dfdl:initiator="%ES: %ES;" to trivially work around this constraint, even though both of these definitions are nonsense.

To avoid repeated discussion of this topic for each of initiator, terminator, and separator, these statements need to be made where ES and WSP* are defined, or in some other central location that discusses DFDL String Literals and whitespace separated lists thereof.

%ES; can never appear as part of any other token. I.e., "%ES;A" is the same as just "A" regardless of what "A" is. So %ES; can only appear as a solitary token in a whitespace separated list of delimiter tokens or nilValue tokens.

Furthermore, %ES; cannot be repeated in the list, since "%ES; %ES;" means the same thing as just "%ES;".

%WSP*; similarly cannot be repeated in the list meaningfully, so that should be prohibited as well.

(In fact repeating any token multiple times in the list can be prohibited.)

%WSP*; cannot be combined with %WSP+;, as the combination is equivalent to just %WSP+; by itself. Furthermore %WSP*;%WSP*; means the same as %WSP*; alone, so that should also be prohibited.

If we add these clarifications, then statements about how %ES; and %WSP*; and their specific constraints for dfdl:initiator and dfdl:terminator and dfdl:separator need not repeat these statements, and the constraints they express do not have obvious gaps.

Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com
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