Troubles with the info-types implementation pattern and with topic nesti

Subject: Troubles with the info-types implementation pattern and with topic nesting in troubleshooting.dtd

Assuming that the spec allows DTDs to be configured so that nested topics won't be present, I have found a design flaw in the DTD implementation pattern for *-info-types. Consider this example from topic.mod:

<!ENTITY % topic.content
"((%title;),
(%titlealts;)?,
(%shortdesc; |
%abstract;)?,
(%prolog;)?,
(%body;)?,
(%related-links;)?,
(%topic-info-types;)*)"

The problem with this construct is that it will not allow %topic-info-types; to be set to empty. The presences of the comma, the parenthesis, and the * occurrence-operator mean that a valid element name must be furnished by the %topic-info-types; parameter entity or the DTD will fail to parse. To correct this, the definition for %topic-info-types; must include the comma, the parenthesis, and the occurrence operator. For example:

<!ENTITY % topic.content

"((%title;),

(%titlealts;)?,

(%shortdesc; |

%abstract;)?,

(%prolog;)?,

(%body;)?,

(%related-links;)?

%topic-info-types;)"

The parameter entity definition in topic.mod becomes necessarily ugly:

<!ENTITY % topic-info-types

", (%info-types;)*"

As also does the one in topic.dtd:

<!ENTITY % topic-info-types

", (topic)*"

This flaw has existed throughout DITA 1.2 and lives on in DITA 1.3. It also suggests that few, if any, have tried to turn off topic nesting.

I discovered this while researching George Bina's question about the "topic" element being available at the end an embedded task topic in a troubleshooting topic. That flaw was caused by the fact that I had neglected to override the the task-info-types parameter entity in troubleshooting.dtd. Specifically, the following parameter entity needs to be added to the TOPIC NESTING OVERRIDE section in troubleshooting.dtd:

<!ENTITY % task-info-types

"task"

Without that override, task.mod defaults the task-info-types value to %info-types; allowing topic to appear as nested topic at the end of task. Of course, my preference would be to set task-info-types to empty in troubleshooting.dtd. And, that's how I discovered that the DTDs won't parse with empty *-info-types.

At any rate, the fix for troubleshooting.dtd and the *-info-types problem need to go on the TC agenda soon.

Best Regards,

Bob Thomas

+1 720 201 8260

Skype: bob.thomas.colorado

Instant messaging: Gmail chat (bob.thomas@tagsmiths.com) or Skype

Time zone: Mountain (GMT-7)

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