In general, enclosing construct's delimiters are also relevant. When scanning for the value of an element with a terminator, there are some circumstances where there might not be a terminator:
- nil value delimiter policy says there is no terminator
- empty value delimiter policy says there is no terminator
- element is optional so if you find enclosing construct delimiter as first character the element is missing

So you *could* design a wholly delimited format where enclosing construct delimiters never needed escaping but it would be a bit restrictive in practice.
Formats that I have seen where enclosing construct delimiters are not escaped usually have fixed length fields.

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

From: Mike Beckerle <mbeckerle.dfdl@gmail.com>
To: "dfdl-wg@ogf.org" <dfdl-wg@ogf.org>
Date: 16/08/2017 15:48
Subject: [DFDL-WG] clarification question on terminators vs. enclosing group separators/terminators
Sent by: "dfdl-wg" <dfdl-wg-bounces@ogf.org>

The DFDL Spec says:

12.3.2 dfdl:lengthKind 'delimited'

On parsing, the length of an element with dfdl:lengthKind 'delimited' is determined by scanning the datastream for the delimiter.

The data stream is scanned for any of

· the element's terminator (if specified)

· an enclosing construct's separator or terminator

· the end of an enclosing element designated by its known length

· the end of the data stream

So if an element has a terminator, are the enclosing constructs' separator or terminator also relevant? Or is ONLY the element's own terminator relevant for scanning, and hence, only the element's own terminator must be escaped if it appears in the content.

For example, in a space-separated group, an enclosed element has a terminator ";". When parsing that element, do spaces have to be escaped if they appear in the content, or does only the terminator ";" have to be escaped?

Strictly speaking it seems enclosing delimiters shouldn't have to be escaped, because the data must have the ";", and spaces are only significant as separators after finding the ";" terminator.

Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com
Please note: Contributions to the DFDL Workgroup's email discussions are subject to the OGF Intellectual Property Policy
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