What does -pub-date mean as endpoint for filters?

The from-pub-date and until-pub-date endpoints for filters are a bit ambiguous in the API documentation.
These pub-date metadata according to the documentarian are about published date.

My question is what kind of published date is meant here i.e. does it include or exclude any of the other *-pub-date endpoints i.e. print-, online- or posted-pub-date?

The total count of e.g. articles may be different depending what pub-date filter I choose so I want to know what it is that I am filtering on, for example the total-results of

https://api.crossref.org/works?filter=has-orcid:true,type:journal-article,until-pub-date:2008-12-31&rows=0 is 23162

https://api.crossref.org/works?filter=has-orcid:true,type:journal-article,until-print-pub-date:2008-12-31&rows=0 is 9436

https://api.crossref.org/works?filter=has-orcid:true,type:journal-article,until-online-pub-date:2008-12-31&rows=0 is 16269



Hello Dave,

Thanks for your post.

So my understanding is that the pub-date filter uses the earliest date from the two if available. So if there are two dates added against the DOI then the earliest will be used and if only one entered then this would be the one used.

You can see this using the example:

I hope this helps.

Many thanks,

Dear Paul,

Thank you for the quick response, explanation and the example.

This was very helpful.