This generates a unique id for use as the
seriesid attribute to the
relation element in the OMF metadata. This id is referred to as
the "series id" or "seriesid".
The seriesid is used to specify a group (or series) of documents which
are related. For example, multiple versions, formats, and translations
of a single document are considered to be in the same series. Thus,
any new version, translation, etc. of a pre-existing document should
inherit the seriesid of the original document. Only document series
which have never been assigned a seriesid in the past should use
scrollkeeper-gen-seriesid to obtain a new seriesid.
ScrollKeeper uses the seriesid of documents to identify which documents
are related to each other. For example, when creating the contents
list, ScrollKeeper must identify if two documents are in the same
series in order to display the most complete set of documents on the system,
using locale fallback for documents which may not be translated into
a given locale, without displaying the same document in two locales.