When a title is issued in multiple series, BIBFRAME does not have a way to associate each series with its numbering. For example, looking at OCLC #45898, as converted by the LC program, we find the following.
bf:seriesStatement "African series",
"Department of State publication" ;
In neither the Work nor the Instance can enumeration be associated with its series for the purpose of search or display. This is a significant step back from current practice.