Comment Submitted by
The current article model describes a set of metadata which not only encodes information about the article itself, but also attempts to capture the context of where, how and by whom the article was published. It also assumes that the article was published at most once, since it only allows for at most one instance of <journal-meta> inside <front> and for at most one instance of <volume> inside <article-meta>.
Furthermore, a closer inspection of the <article-meta> model reveals a number of metadata elements which do not relate with the article itself, but to the volume and/or to the issue where this article was published under. Examples of such elements are <volume>, <volume-id>, <volume-series>, <issue>, <issue-id>, <issue-sponsor>, <issue-title>, <issue-part>, <isbn>, etc. Finally, the entire <journal-meta> model defined under the article <front> element describes metadata about the publication that hosts the article (<journal-id>, <journal-title-group>, <issn>, etc) and the publisher that publishes it (<publisher-name>, <publisher-loc>).
An immediate implication of this logic is that articles belonging to the same issue repeat a lot of their metadata information, since that belongs to the journal, volume or issue and not to the article. Repetition is prone to errors and metadata inconsistencies are hard to resolve.
On the other hand, when an article is published in two places simultaneously, such as for example published in a printed issue and at the same time placed in an electronic-only collection, the article XML fails to capture metadata about one of its publishing instances, owing to the above limitation in the model. An attempt to enhance the current model to allow for multiple publication instances in the <article> model will require a major restructuring of <article-meta> to extract all volume and issue level information out of its scope.
Another limitation with the current association of publisher, journal, volume and issue metadata with the article is the fact that information associated with these higher-level publication entities cannot be encoded in the article XML. Examples of such information form a) a PDF for the entire issue, b) an index for the issue, c) a PDF for the Table of Contents, d) a pointer to the "instructions to the authors" section, e) the issue DOI and self URI, f) a link to all issue ads, g) links to issue-level supplementary material, h) the issue cover image and its associated caption, i) links to related issues or publications.
Finally, information for the encoding of the Table of Contents and its associated elements lies dispersed across the article XMLs of an issue rather than be isolated in a single place which lists all articles participating in the Table of Contents along with headings, page numbers, issue titles, etc.