Mike

I ran a test with IBM DFDL using the dfdl:separator, dfdl:escapeCharacter and dfdl:escapeEscapeCharacter in your example. For each element in the sequence I received ...

CTDV1466E : DFDL properties 'separator' ('/') and 'escapeCharacter' ('/') cannot include the same value.
CTDV1467E : DFDL properties 'separator' ('/') and 'escapeEscapeCharacter' ('/') cannot include the same value.

Changing the escape scheme to be escapeBlock as per your example, I get for each element:

CTDV1467E : DFDL properties 'separator' ('/') and 'escapeEscapeCharacter' ('/') cannot include the same value.

So we must have discussed this in the past and concluded that it's an SDE.

I don't get an error for dfdl:escapeBlockEnd itself though, I assume because once inside an escape block we are no longer looking for delimiters.

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: 03/05/2021 20:23
Subject: [EXTERNAL] [DFDL-WG] Clarification: priority of delimiters vs. escape chars
Sent by: "dfdl-wg" <dfdl-wg-bounces@ogf.org>

Consider two elements in a sequence, dfdl:separator="/ // ///" with escapeCharacter="/" and escapeEscapeCharacter="/"

I did not spot language in the spec that makes it clear what gets priority, interpreting a character as an escape char or escape-escape char, or interpreting it as a delimiter.

Consider data "foo///bar".
1. I could interpret that as escapeEscape, escape, and minimum length separator "/"
2. Or I could interpret that as "///" maximum length separator, with no escaping.
3. Or it could be an SDE.

To me, we'd be best off if the escapeCharacter was not allowed to be (SDE) the same as the first character of any in-scope terminating delimiter. We're not doing anyone any favors by allowing this.

Likely a similar restriction would be needed for escapeBlockEnd, that the value of this property could not be a prefix of any in-scope-terminating delimiter, and escapeEscapeCharacter could not be the same as the first character of the escapeBlockEnd.

E.g., dfdl:escapeBlockStart="/" escapeBlockEnd="/" dfdl:separator="/ // ///"

With data "/foo///bar"

Is that
1. escapeBlockStart, foo, escapeBlockEnd, separator "//" bar ?
2. Or escapeBlockStart, foo/, separator "/" bar ?
3. Or SDE?
Comments?

Mike Beckerle | OGF DFDL Workgroup Co-Chair | Owl Cyber Defense | www.owlcyberdefense.com
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