The a,b,c values mean nothing to Crossref and serve no purpose in this context and they create unclean data. They want just the date, so we should use the iso-8601-date value instead
In the case above, it will prefer the numeric value for year taken from the iso-8601-date attribute, or if that is not available then it will use the date text as written, e.g. 2004b.
For example, this:
Is getting converted to
The a,b,c values mean nothing to Crossref and serve no purpose in this context and they create unclean data. They want just the date, so we should use the iso-8601-date value instead