Re: [dita] Rationale for content model of definition list entry

["Don R. Day" <donday@donrday.com>]

On 5/17/2015 8:33 AM, Kristen James Eberlein wrote:

I was asked about the content model for definition lists this past week.

Why does the content model for <dlentry> allow multiple instances of <dt>? I can understand multiple instances of <dd> -- a term often has multiple definitions -- but a use case for multiple (primary) terms eludes me.

FWIW, the content model for <dlhd> only permits zero or one <dthead> and zero or one <ddhd>.

Digging back to the origins:

This quirk reflecs the premise that the base models throughout DITA are intentionally rich to support many possible use cases via specialization. In the case of dlentry, I seem to recall that we observed precedent cases of multiple terms both in former IBMIDDoc and in HTML content that we examined. If you were documenting error codes or flags in software, for example, several codes might all point to a common cause or response. In hardware, the same would go for indicator lights or sounds. The nature of the dd "column" to behave like the singular key can be seen also in simpletable where any column can be designated as the @keycol. Hence column 1 is not always necessarily the "single value lookup" column in the general case of who-knows-what-data.

The heading case is different since this involves a label for the column, so a single label of "Names" may reflect subsequent column data that consists of possible plural child items. Simpletable may have multiple strows of stheads, but that is mostly a quirk of the open base model for specialization--most users create only one row of heads, which acknowledges the same intent as the dlhead constraint.

This may have been covered in the FAQ-like topic I contributed about DITA quirks. We might consider adding this discussion into that topic if it adds anything useful.

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Don R. Day
Founding Chair, OASIS DITA Technical Committee
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"Where is the wisdom we have lost in knowledge?
Where is the knowledge we have lost in information?"
--T.S. Eliot

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