[1] 計算機システムにおける暦の指定も参照。
; recur-rule-part is extended from RFC 5545
recur-rule-part =/ ("RSCALE" "=" rscale)
/ ("SKIP" "=" skip)
rscale = (iana-token ; A CLDR-registered calendar system
; name.
/ x-name) ; A non-standard, experimental
; calendar system name.
; Names are case insensitive,
; but uppercase values are preferred.