{{- /* Entry number of a post: 1-based position in date order across all posts, zero-padded to three digits. */ -}}
{{- $p := . -}}
{{- $no := 0 -}}
{{- range $i, $e := (where site.RegularPages "Section" "posts").ByDate -}}
  {{- if eq $e $p }}{{ $no = add $i 1 }}{{ end -}}
{{- end -}}
{{- return printf "%03d" $no -}}