Adding implicit string values

Michael's TEI reference example makes me think that there is another missing feature that we may want to consider.

If there is some grammatical furniture in an input parse, we can choose to discard it using the `-` mark, and suppress the corresponding rule in the grammar from being serialised as an XML node.

Thus, something explicit in the non-XML format can become implicit in the XML format.

Michael's use case is an example of where we might want to do the opposite: take something implicit in the non-XML format and make it explicit in the XML format.

We can do that, as Michael discusses, by adding a rule name that we might not want in our final output and processing further, but I think it would be better if we can do as much as possible "in camera" rather than "in the dark room".

Perhaps we could consider a `+` mark to complement the `-` mark;  the effect would be to create some XML node that need not be present in the parsed input:

               citation: article-citation; journal-citation; book-citation.
      -article-citation: +article-citation-level, author, title, journal, volume, locator, date.
      -journal-citation: +journal-citation-level, journal.
         -book-citation: +book-citation-level, author, title, location, publisher, date.
@article-citation-level: "a".
@journal-citation-level: "j".
   @book-citation-level: "m".

Tom

_________________
Tomos Hillman
eXpertML Ltd
+44 7793 242058
On 13 Apr 2021, 02:54 +0100, C. M. Sperberg-McQueen <cmsmcq@blackmesatech.com>, wrote:
>
> So we start with
>
> <article>Alka-Seltzer, L. Untersuchungen über die tomatostaltische Reflexe beim Walküre. *Bayreuth Monatschr. f. exp. Biol.* 184, 34-43, 1815.</article>
> ...
> <book>Hun, O. & Deu, I. *Tonic, diatonic, & catatonic stage-distress syndromes.* Basel, Karger, 1960.</book>
>
> and use simple grammars to parse these into a richer tagging. (Trying to show how these would be tagged, I realize I can’t get these into TEI on a single pass, because the TEI output wants <title level=“j”> for article titles, <title level=“j”> for journal titles, and <title level=“m”> for book titles, and we don’t have any literal “a”, “j”, or “m” in the data to use to populate the ‘level’ attribute.