Sequence number of a document within the type of sequence named by the element to which this attribute is attached: on a <volume> element, the sequence within the volume; on an <issue> element, the sequence within the issue; on an <fpage> element, the sequence within a single page; and on an <elocation-id> element, the electronic sequence.
For journals (such as continuous-makeup journals) where more than one article can start on a single page, this attribute can record a sequence number or letter to differentiate one article from the other articles on the same page. For example, the first article to start on page 62 might be given a sequence of “62a”; the sequence letter would be “a”, with a sequence letter “b” for a second article, etc.
|Text, numbers, or special characters||The number of the document in a sequence of documents within a volume, issue, electronic compilation, or even on the same page. For example, for continuous-makeup journals that start more than one article on the same page, this attribute indicates a sequence number or letter for one of the articles, such as “a”, “b”, “c”; or “1”, “2”, “3”. For example, a value of “2” could mean “554-2”, page 554, second article.|