first page number: {{ExtractFirstPageNumber|pages=xi-vv#var: varFirstPageNumber}}
{{ExtractFirstPageNumber#if: {{IsNumber|pagesvalue=abc{{var: varFirstPageNumber}}|}}<!-- -->|<!-- --><!-- regular number: store as is -->{{#set:First Page={{#var: varFirstPageNumber}}|}}<!-- --><!-- -->|<!-- --><!-- not a number: see if it is roman -->{{#set:First Page=0|}}<!-- --><!-- --def>}}